On a cold October night, Richard Ratcliffe, not for the first time, was watching a play about his wife’s ordeal in an Iranian prison. Nazanin Zaghari-Ratcliffe, a dual-national British-Iranian, has been in detention in Tehran since her arrest on 3 April 2016. She is accused of spying – a charge she denies. The play was being staged in the London Metropolitan University on Holloway Road, where Zaghari-Ratcliffe, on a scholarship from Iran, studied communications management between 2007-2008.

Ratcliffe was sitting in the front row. Beside him sat Ana Diamond, a woman who was incarcerated in the same prison as Nazanin until 2016, and Diamond’s father. As the play unfolded, Diamond’s father, who had also spent years in an Iranian prison, broke into loud sobbing, making it nearly impossible to hear the dialogue. Even though he and his daughter were now free, watching the play forced him to relive the trauma of imprisonment.

By contrast, Ratcliffe, an accountant, sat impassively through the 90-minute performance, which began with his own hunger strike outside the Iranian embassy in London, last summer. He observed the unfolding drama – his wife, tearful and pleading, the revolutionary guard who abused her in prison, a smug Foreign Office spokeswoman, his own agony – without betraying any emotion. The set included a calendar marking the days his wife has spent in captivity, and the script quoted from letters and poems she has written to Richard: “I would like to marry you again. It would be the best thing to happen to me. I would like to plant one tree to mark my freedom.”

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Later, Ratcliffe explained how he managed to control his emotions by casting himself in the role of a neutral theatre critic, noticing small changes in the production since the last time he saw it. After the play finished and the cast had taken their bows, Ratcliffe stepped up on stage to answer a familiar round of questions about the prospects for his wife’s release, and her state of mind. The campaign, he explained, is not just about “getting the right people to listen”, but letting Nazanin know that people care about her fate. With characteristic restraint and politeness, he urged the prime minister to help them: “With all the distractions of Brexit, please do what you can.”

The day after seeing the play, day 1,304 of his wife’s captivity, Ratcliffe told me, he suffered a delayed reaction. He felt too depressed to get out of bed. By now, it was a familiar experience. “It is how I operate,” he said. “It is a coping mechanism. I keep myself incredibly busy and then it all kicks in.”

There is a particularly senseless and unjust quality to the story of Zaghari-Ratcliffe. She was arrested at the end of a two-week trip to see her parents with her three-year-old child, and authorities used her dual nationality and her work as a project manager for the charitable arm of Thomson Reuters Foundation to claim she was a spy seeking to overthrow the Iranian state. Her case represents a growing trend of state hostage-taking, in which secret police pick up innocent people, often dual nationals, and use them as bargaining chips in wider negotiations with a rival state.

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In the case of Zaghari-Ratcliffe, it seems that she is a pawn in a 40-year dispute between Britain and Iran. This dispute concerns a long-standing £400m debt Britain owes to Iran: the advance payment for a shipment of tanks that was never fully delivered. Quite why that debt has never been paid is a story of British arrogance, secretive arms deals, American sanctions, Whitehall inertia and infighting at the highest level of government.

Some of the most egregious blunders in this sorry episode have been committed by the current prime minister, who promised to leave no stone unturned to secure Zaghari-Ratcliffe’s release, but instead, mainly through error, has blocked her road to freedom. Ratcliffe is a balanced and rational man, but it is hard to overstate the contempt he feels, in his bleaker moods, for Boris Johnson.

The story of Britain’s debt to Iran, like so many political stories in the Middle East, starts with oil. When the Shah of Iran was installed in 1953, after a coup aided by the British, he planned to become the dominant power in the region. By the 1970s, the Shah, benefiting from booming oil prices, had become one of the largest purchasers of British-manufactured arms; between 1972-1978, almost a quarter of all British arms exports were destined for Iran. The single biggest deal, signed in 1971, was for the sale of more than 700 Chieftain tanks, at the time the most powerful battlefield tank, prized for the accuracy of its guns.

This deal, which was worth £115.5m, was negotiated between an agency owned by the Ministry of Defence, Millbank Technical Services (MTS), and a confidante of the Shah, an Iranian called Shapoor Reporter, who had previously worked for British intelligence. As part of the contract, Reporter would receive 1% of the price – an unofficial fee for persuading the Shah to choose the British Chieftain over the rival German Leopard tank. Reporter’s informal brokerage fee was agreed by MTS and paid into a special fund administered by the private investment bank Kleinwort Benson.

The UK was perfectly aware that, whether this 1% fee went to Reporter or to the Shah himself, none of it would reach Iranian state coffers. It was part of the role of MTS, which operated as the government’s arms sales company with subsidiaries across the old empire, to pay such informal brokerage fees with minimum parliamentary scrutiny. Harold Hubert, director of army sales at the MoD, explained in 1972 that there were “advantages in MTS ... passing on the douceurs”.

Reporter was knighted in 1973 for “services to British interests in Iran”. In December 1974, the Shah ordered a further 1,800 tanks, mainly the latest version of the Chieftain. The Iranians were required to pay 75% of the fee up front in order to cover the cost of getting the tank’s armour into mass production and to equip the main factory in Leeds. For Britain, where the economy was stalled in the middle of a balance-of-payments crisis, the timing of this deal was perfect.

However, to the embarrassment of all involved, details of the secret payments would emerge two years later, during an unconnected corruption trial. In 1976, a British serving officer, David Randel, appeared in court charged with taking £25,000 in fees in relation to a contract to install British radar equipment into the Chieftain tanks. During cross-examination, the head of MTS, Sir Lester Suffield, disclosed that a £1m commission had been paid to Reporter because “his advice is tremendously important to any British company trying to sell to Iran”. Since the cost of the commission was included in the deal, it meant Iran was paying inflated prices to enrich officials and the Shah himself. The Shah, already facing anti-corruption protests in Tehran, tried to insist he had not known of the fees, but the court was told that “the Shah [had] set up a special fund to receive bribes which otherwise would have found their way to officials”.

Sir Anthony Parsons, the British ambassador to Tehran, wrote in October 1977: “I am seeing the Shah frequently about the unfolding of this trial and am having a difficult time of it.” Parsons recalledthat the Shah “could not tolerate the insinuation that he had been receiving money paid by us to Reporter”.

To protect its relationship with the Shah, Whitehall hastily concluded it could not confirm whether he had been aware of the commissions paid by MTS, let alone whether he was personally benefiting from them. But by late 1978, the UK could see the Shah was losing his grip on power. When he was ousted in January 1979, desperate attempts were made to win favour with the new regime, and the Shah, Britain’s former ally, was refused asylum in the UK. The then foreign secretary, Lord Owen, later wrote: “There was no honour in my decision, just the cold calculation of national interest.” But the harsh treatment of a former ally was to no avail, officials told the prime minister, Jim Callaghan. “The changes in Iran have dealt a major blow to western interests in the Gulf.”

Facebook Twitter Pinterest Ratcliffe meeting Boris Johnson, then foreign secretary, in London in November 2017. Photograph: WPA Pool/Getty Images

That blow was most keenly felt in the defence industry. British military exports to Iran would be halved in a year, with the loss of 35,000 jobs. A senior commercial officer at MTS later recalled “something akin to panic broke out in the Royal Ordnance Factories”. Export approvals for all military contracts to Iran were withdrawn. The MoD was faced with the nightmarish prospect of wholesale redundancies.

The only advantage for Britain was that, while the Iranians had paid almost all the agreed fees for the tanks upfront, only a small number had been delivered. When the Iranians formally terminated the tank contract on 6 February 1979, Iran had received only 185 tanks, worth £56m. They demanded that £250m, which they had paid in advance, must be returned. But MTS kept the money, passing £120m to the MoD and keeping the rest hidden in its accounts. Some of the tanks already built but not yet sent to Iran were sold on to Jordan, and some were bought by the British army, renamed as Challengers.

As it turned out, the advent of a revolutionary Islamic regime in Tehran, which had looked disastrous for British interests, did not put an end to the British government’s opportunities to make money in the Gulf. On the contrary, war between Iran and Iraq, which broke out in 1980, proved highly profitable. The UK’s declared position throughout the Iran-Iraq war was neutral, but as the Scott inquiry into arms sales to Iraq later revealed, the true policy was to sell arms to both sides, in breach of an arms embargo.

In 1982, MTS was rebranded as International Military Services (IMS) – still a subsidiary of the MoD, but now a private company and, as such, less accountable to parliament. IMS kept an office in Tehran and continued selling arms to Iran. At the same time, IMS was given the contract to repair any Chieftain tanks captured by Iraq from Iran. As Alan Clark, then defence minister, later admitted: “The interests of the west were best served by Iran and Iraq fighting each other, and the longer the better.”

Britain had paid fees to a corrupt Shah, then pocketed Iran’s money without delivering the tanks before breaking a British arms embargo. “The Iranians have long regarded the British as perfidious and corrupt, accurately or not,” said Jack Straw, the former foreign secretary. “This whole Chieftain tank episode just confirms them in this view.”

Britain’s cynical policy of arming both sides in the longest conventional war of the 20th century, which left 500,000 dead, was not something the Iranians would forget. More than a decade after the first arms deal was cancelled, Iran had taken delivery of fewer than 10% of the tanks for which the Shah had paid. In 1990, the Iranians embarked on arbitration proceedings to demand that IMS hand back the money. It was the start of an extraordinary legal marathon, much of it played out behind closed doors in the permanent international arbitration court in The Hague.

In May 2001, after more than a decade of claims and counterclaims, the court in The Hague declared that IMS must pay the Iranian ministry of defence (Modsaf) £141m plus interest from 1984 to the date of payment. The total sum was estimated to be about £380m. IMS was also told it would have to pay the costs incurred by Modsaf during legal proceedings over the previous decade.

But this was far from the end of the story. IMS immediately contested the judgment, and in cases where awards by the arbitration court are contested, they require an enforcement order in the relevant domestic court.

Now the gruelling legal battle entered its next phrase. In July 2001, Modsaf sought to have this award enforced in a British court, which IMS resisted by launching another appeal. In December 2002, IMS and Modsaf agreed that IMS would transfer a sum of £382m to a court funds office – to be held as security pending the IMS appeal. (The balance, with interest, is now over £500m.)

In December 2006, the Dutch appeal court slightly lowered the amount the UK should pay. But the indefatigable lawyers for IMS were dissatisfied with the size of the reduction and, in April 2008, submitted a further appeal. (When the EU imposed sanctions on Modsaf in June 2008 because of its links with Iranian nuclear research, IMS took this as a further reason not to pay.) However, in April 2009, this appeal was roundly rejected by the Dutch supreme court in a damning ruling.

It looked as if IMS had run out of road. Payment of the debt was overdue. One former Labour cabinet minister said: “I am not sure whether IMS have been under much political direction. It looks like they have just been pissing about for the sake of not very much money.”

This prolonged battle has contributed to the historic mistrust between Iran and Britain, which has periodically erupted in hostilities. In November 2011, Iranians stormed the British embassy in Tehran, in protest at the UK’s role in blocking the Iranian nuclear programme. Protesters scaled the gates, broke the locks and entered the compound. Inside, the demonstrators burned the British flag, smashed windows, destroyed paintings, sprayed graffiti and set a car ablaze.

After this break-in, the Iranian ambassador to the UK was expelled and the British embassy in Tehran was closed. It was not reopened until 2015, after Britain and other western powers signed the nuclear deal, which lifted sanctions in return for Iran halting its nuclear programme and allowing an intrusive UN inspection regime. By then, potential reformers, such as President Hassan Rouhani, were in the ascendant.

It was during this period, in March 2016, as Iran started an era of wary engagement with the west and tensions eased, that Zaghari-Ratcliffe flew to Tehran with her daughter, Gabriella. There seemed no cause for concern. She had made the trip every year since she left Iran in 2007, twice with her husband. She was eager for her ageing parents to spend time with their new grandchild.

Zaghari-Ratcliffe had studied English in Tehran before she went to London alone on a scholarship to complete a masters degree. She had met Ratcliffe, then on an accountancy graduate course, at a conference on Palestine. He was an hour late for their first date and when he finally showed up, she laughingly punched his arm. Still, the date couldn’t have gone too badly. As they got to know each other better over the following months, they found that, despite their different backgrounds, they had much in common. They had the same sense of humour, and they had both been brought up in middle-class households where family was everything. Ratcliffe also admired her boldness. “It was very intrepid of her to come to London,” he said. “She was very genuine and straightforward. She had that wonderful enthusiasm, and a desire to explore a new country with great open eyes.”

Three years after they met, he proposed. She posted on her Facebook page: “A big thank you to God and to Richard’s God”. The couple married in 2009 and threw three parties to reflect their different cultures. Ratcliffe had himself been out to Tehran twice to present his credentials as a prospective son-in-law. “She had two sisters and a brother. And her father, an electrical engineer, was very proud his kids had all gone to university,” Ratcliffe recalled. “If there was any politics discussed, it was family politics.”

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As Zaghari-Ratcliffe and her daughter were heading home to the UK on 3 April 2016, she was arrested at the airport, by agents from Iran’s Revolutionary Guard (IRGC), the powerful militia that operates in parallel with the Iranian military. She was taken to a prison in Kervan in the south of Iran and kept in solitary confinement. Her parents were summoned to take their grandchild home with them. For the next 55 days, she was not allowed to speak to her husband on the phone. “We knew virtually nothing about what happened to her, but I knew she would be tortured by the separation from Gabriella,” Ratcliffe said.

Two months after Zaghari-Ratcliffe’s arrest, the authorities described her as a ringleader in a revolt against the Islamic republic and took her to Evin prison in Tehran. In August 2016, following a trial behind closed doors, she was sentenced to five years in prison on charges relating to national security. She was only given access to her lawyer the day before the court session, and the lawyer was given just five minutes to defend her. These same restrictions applied during the subsequent appeals process in Tehran.

For the first nine months after she was arrested, Zaghari-Ratcliffe was kept in total isolation. She has since suffered from mood swings, depression, panic attacks and anxieties about her physical health. At times she has been chained to a bed in a psychiatric wing. Her parents visit every week. Until last year, when Gabriella was brought back to the UK, they would bring her to visit her mother. Zaghari-Ratcliffe speaks to her husband by phone three times a week for 10 minutes. All calls are monitored. “The first calls I just tried to reassure her that we were still here for her, and that I loved her,” he said. “There is nothing else that matters. She had been fed all sorts of poison – that I was off with other women.”

Last June, Zaghari-Ratcliffe wrote a letter marking Gabriella’s fifth birthday. “She teaches me now that there is a silver lining in every cloud, and that there is a home, a very warm home waiting for us to go to, where Daddy has been waiting for us for over three years. My most beautiful baby girl, you are wise beyond your age, with the most amazing imagination. You see the world in primary colours, you look out for the unicorns.

“Your visits and smiles make my world brighter. I know we have been through dark years – perhaps the darkest of our lives – but we have had each other. No one can take us apart. No politics, walls, or even prisons.”

It was agonising for Zaghari-Ratcliffe to see her daughter so rarely. A few months after Gabriella’s birthday, she wrote to her husband: “My heart pounds much more than usual every Sunday morning – when I get to see my Gabriella Gisou in the visiting room of Evin prison, full of excitement. When the door of the visiting room opens, and the prisoners are allowed in, it is my little girl who runs towards me first, calling out my name, rushing to my cuddle. Those brief minutes might be the shortest of cuddles, but without doubt the most beautiful and uplifting cuddles in the whole world. They are my world.

“But then comes the stress – Sundays slip so soon through my hands, and fade away in the fog of the cell.”

Zaghari-Ratcliffe was just one victim of a wave of arrests of as many as 20 dual nationals in Iran that took place during 2015 and 2016 – academics, businessmen and individuals who could be linked to a foreign NGO were picked up, including Austrians, Canadians, Britons and Chinese-Americans. Ratcliffe believes the IRGC views dual nationals, a concept Iran does not recognise, as unwelcome symbols of reformist attempts to break down barriers between Iran and the world. This strategy is ongoing. In September 2018, an Australian academic, Kylie Moore-Gilbert, was arrested in Tehran and sentenced to 10 years in prison. In leaked letters published earlier this week in the Times, Moore-Gilbert protested her innocence and warned that her detention is destroying her mental health.

The timing of Zaghari-Ratcliffe’s arrest, just before a hearing on the Chieftain tank debt issue was due to take place in the London high court, seems significant. Three months earlier, in January 2016, the US had refunded Iran $400m (£300m) for undelivered military equipment, and this led to the release of four Americans, including the Washington Post reporter Jason Rezaian. Ratcliffe is convinced the IRGC came to see his wife as another bargaining chip to ensure a debt was paid: “The guards thought, crudely: ‘We want to get our money, so we must arrest someone,’” Ratcliffe told me. One former minister says: “The Iranians are very transactional, and her arrest was viewed as the start of a transaction.”

In the weeks after his wife’s arrest, Ratcliffe had been strongly advised by the Foreign Office to say nothing in public, while diplomatic efforts were made to secure her release. But knowing that his wife was being held in solitary confinement, and initially debarred from speaking to her by phone, Ratcliffe took the decision to defy that advice and, in May 2016, went public with an online petition. Over the following months, he found himself trying to run a campaign to keep her in the public eye. As he overcame his natural shyness, the campaign grew into a force calling not just for his wife’s release, but an end to state hostage-taking altogether.

Asked if he worries that, on reflection, going public was an error, Ratcliffe said: “I don’t think I am in an emotional space where you can have doubts. When it is all over and we are out the other side, there will be a space to reflect, but at the moment we are in the middle of a battle, so we keep going on. Our strategy has worked no worse than anyone else’s. I tell the Foreign Office: ‘It’s clear there are good reasons why we are doing what we are doing. I want to make my problem your problem.’” He added: “The government’s failure to settle this case is not because they do not care. It is because they do not care enough. There is no lack of sympathy, it is just that sympathy is not going to get us home.”

Facebook Twitter Pinterest Nazanin Zaghari-Ratcliffe, who has been imprisoned in Iran since 2016. Photograph: Family Handout/PA

Campaigning for his wife’s release has been a learning process. “I used to work for the National Audit Office, so my biggest previous political act was sometimes to mutter under my breath,” he said. Now, when the politics around the campaign intensifies, he finds the attention hard to deal with. “You can issue a press release, and six hours later the media will want to know: ‘What’s the next step?’”

In early November 2017, the attention became overpowering when Boris Johnson, as foreign secretary, made a blunder that set back Zaghari-Ratcliffe’s cause. While she has always maintained that her visit to Tehran was purely to see her family, Iran had accused her of running a “a BBC Persian online journalism course which was aimed at recruiting and training people to spread propaganda against Iran”. It is true thatbetween February 2009 and October 2010, Zaghari-Ratcliffe had worked for an online BBC World Service Trust journalist training course. But it was a purely administrative role, booking Iranian and other students on courses. She then left to work for Thomson Reuters Foundation, the charitable arm of the news organisation.

In the middle of a long foreign affairs select committee session in November 2017, Johnson blurted out to MPs that “she was simply teaching journalism, as I understand it, at the very limit”. It was intended as a statement in her defence, but it directly contradicted Zaghari-Ratcliffe’s own account. The Iranian judiciary claimed that Johnson’s inadvertent confession proved it had been right about the real reason for her visit. “Johnson’s statement annulled all the claims in the past year made by British media who said that she was only visiting Iran for humanitarian reasons,” declared Iran’s state broadcaster.

It took Johnson 10 days to issue a half apology. However, in seeking to protect his personal reputation afterwards, he made matters worse. After stalling for weeks, Johnson finally agreed to hold a meeting at the Foreign Office with Ratcliffe, Ratcliffe’s father and his MP, Tulip Siddiq. On the morning of 15 November 2017, the day their meeting was scheduled, the Sun newspaper’s front page carried an article marked exclusive: “Iranian officials present a multimillion shopping list to free Nazanin. The demands include settling a 38-year-old demand for £400m arising from a Chieftain tank deal.” The Sun story argued that the debt was the true cause of Nazanin’s continued imprisonment, so implying that Johnson’s gaffe was not significant in her plight. Ratcliffe was convinced Johnson had placed the story to make him look better.

“At the meeting, the foreign secretary was quite charming, but refused to apologise for what he had said at the select committee,” Ratcliffe recalled. “Near the end of the meeting, we showed him a copy of the Sun story. Boris said he had never seen the article. At that point, Alistair Burt, the Middle East minister, just left the meeting. I think he was horrified by what Johnson had done and did not want to be party to it.”

The following day, the Sun reported that Johnson, with the chancellor Philip Hammond, had “quietly authorised that £450m be handed over”. The Iranians were sufficiently convinced for their ambassador to London to announce on the messaging service Telegram a day later that “the debt was to be transferred in the coming days”.

So when Johnson went to Tehran a few weeks later, in December 2017, expectations for Zaghari-Ratcliffe’s release were high. Her fellow prisoners started to ask her how she was going to distribute the few possessions she had with her in prison. She began to make leaving presents, including little makeup bags for each of the prisoners, made from a floral print fabric. She was a great knitter and, since the snows had come to Tehran, a couple of the prisoners asked her if she could knit them an “English” woolly hat before she left. But the snows came and went, and she remained in jail.

In retrospect, Ratcliffe says, he believes that Johnson’s aides had briefed Sun journalists about the breakthrough on the debt payment without truly knowing if the relevant government departments, including the MoD, were signed up. On his return from Tehran, Johnson told Ratcliffe he should go quiet for three months or so. Ratcliffe was plunged into despair.

The fact that Zaghari-Ratcliffe’s fate is tied to the ongoing dispute over Britain’s debt to Iran is, by now, hard to deny. The IRGC told Zaghari-Ratcliffe as much during her initial interrogation in 2016. The Iranian deputy prosecutor said the same in May 2018. Again that year, Judge Abbasi, the head of judicial affairs inside Evin prison, was reported as saying to Zaghari-Ratcliffe in court: “Every time I request to review your case, this is the answer: ‘The UK has not paid’ and that is why we cannot do anything.”

Senior Iranian diplomats in London privately admit there is a link between Zaghari-Ratcliffe’s detention and the debt, and question why successive British governments have not done more to resolve the issue. Jack Straw now admits he did not do enough to pursue the issue in office. Ratcliffe’s team of lawyers have written at length to cabinet ministers including Johnson and Hammond, urging them to use greater imagination and find a way to pay at least the principal. Their letters mostly go unanswered. One reply from Johnson, in May 2018, stated that there is no connection between the debt and her detention.

That, at least, is the government’s line in public. But ministerial sources have confirmed that this has been the subject of heated debate behind closed doors. According to a ministerial source, last year, Foreign Office minister Alastair Burt had a stand-up row with the defence secretary Gavin Williamson about his refusal to find a way to pay the debt. Another former minister said of the handling of the case while Theresa May was prime minister: “Hammond was scared stiff he would be sanctioned by the US if he paid. Williamson just thought: ‘I am not going to fucking help the IRGC.’ May was useless, just a coward, as she was about everything.”

Ratcliffe found Jeremy Hunt, who replaced Johnson as foreign secretary in July 2018, empathetic, but he was not been able to succeed where his predecessor failed. In November 2018, Hunt went to Tehran to meet the foreign minister, Mohammad Javad Zarif, and came away empty-handed. At the time of his visit, he said Zarif did not even pretend Zaghari-Ratcliffe was guilty. Her fate, Zarif said, lay with the judiciary, and not his department, but Hunt’s plan to meet the justice minister fell through.

In March 2019, Hunt, overruling advice from the Foreign Office, granted Zaghari-Ratcliffe diplomatic protection. Ratcliffe said: “There is a Foreign Office instinct about not creating precedents. They worried that the moment Nazanin was given diplomatic protection, then other victims of gross human rights abuses would have a reasonable claim to say that they deserve protection, too.”

Facebook Twitter Pinterest Ratcliffe and Zaghari-Ratcliffe with their daughter, Gabriella. Photograph: Family Handout/PA

Another Foreign Office minister, Sir Alan Duncan, although not responsible for the Middle East, became involved in Zaghari-Ratcliffe’s case because he knows the Gulf well as a former oil trader. He proposed paying the debt into a new escrow account so Iran could receive the money owed in the form of humanitarian aid. The debt might not then be subject to US sanctions. In his resignation letter, in July 2019, Duncan said he “remained deeply upset that some fruitful discussions I had initiated about the possible release of Zaghari-Ratcliffe were brought to such an abrupt halt”. It is not clear if the premature briefings led to his plan being shelved, but it is now being re-explored by ministers.

Meanwhile, in the British courts, IMS has carried on its secretive legal trench war with Iran. At first there was a ban on reporting the case, as is typical in commercial arbitration cases. But in May 2019, after an intervention by Ratcliffe’s lawyers and the Sunday Times, Mr Justice Phillips lifted reporting restrictions, and for the first time it was possible to see the scale of IMS resistance to paying the debt. On one occasion, Iranian officials with visas granted by the Foreign Office arrived in the UK on a mission to enforce the Dutch court order. In spite of their legal status, the Home Office held them in a detention centre for nearly a week.

In July 2019, and again in a follow-up hearing on 7 October, the law firm Clifford Chance, representing IMS, scored a legal victory, worth millions of pounds. At a hearing, Mr Justice Phillips declared IMS did not have to pay Modsaf interest on any of the money it had withheld after 2008, the date Modsaf came under EU sanctions. In a briefing afterwards, IMS, apparently savouring its victory, declared that at the next hearing it plans to argue that, because of sanctions, it should not have to pay Modsaf any of the £379m it owes. At no point during the hearing, or afterwards, was Zaghari-Ratcliffe’s name mentioned.

The case rolls on, week after week, month after month. Just this week, Ratcliffe sat listening in court room 70 of the Royal Courts of Justice, as three appeal court judges heard IMS and Modsaf continue their seemingly endless argument as to whether interest is payable on the debt.

Ratcliffe, for his part, while trying to follow the legal back-and-forth, is learning to be a father again. In October, Zaghari-Ratcliffe’s brother brought Gabriella, now five, to live with her father, but it is a mutual learning process. She speaks little English, and her uncle has to help with translation. After years apart, Ratcliffe is adjusting to having his daughter back at home in Hampstead.

“Now there are many cuddles, but at first it was a bit like being a stepdad,” he said. “You have to earn your right again to parent, to discipline and be trusted. Gabriella has come over with no control of the situation and there are parts of her wanting to be back in Tehran watching cartoons she can understand. She does not like talking about Mummy being in prison, but she has started to ask why others were being let out of prison and she seems to understand what prison is. She is disoriented and aware that we have made promises we have not been able to keep.

“She has internalised a lot. She notices, for example, if there are any cameras on a bus or a tube. At the moment, she does not dwell on loss or injustice and unfairness. When she is six or seven, she will have a keen sense of right and wrong that she does not have yet.”

As for the campaign, Ratcliffe admits it has worn him down. “At this point it is a bit hard to know what to do,” he said. “We sort of had this idea of a staircase where we escalate every so often, and go up a level. But once you get to a hunger strike on the street, there are not many places you can go from there.”

Ratcliffe has had to endure the rising tensions between Iran and the west, knowing that events way beyond his control can render his campaign irrelevant. All the time he is trying to read the shifts in government thinking, picking up fragments from wherever he can. On Thursday, Ratcliffe will be meeting with Johnson for the first time since he became prime minister. He plans to tell Johnson that “doing nothing is not an option” and wants to know if there is a strategy in place or not.

Meanwhile, he is left to worry about his wife’s worsening health. Since the winter of 2017, when hopes for her release came to nothing, Zaghari-Ratcliffe has been deeply depressed. “She cannot cope. She is trying to be as clear as possible that she cannot cope,” said Ratcliffe. “She has undertaken four hunger strikes. She is set apart from her daughter. The Foreign Office just needs to be aware that we do not have the luxury of time. Both governments can play this game of poker with one another. We are the ones who are paying the cost, and she cannot pay it for much longer.”

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