This week Aras Amiri from north London was convicted and sentenced in Iran to 10 years in prison for organising Iranian cultural events in the UK for the British Council.

It brought back memories of the sentencing of my wife Nazanin Zaghari-Ratcliffe on similar charges in 2016 – and the tearful weeks failing to make sense of it all. Aras’s case has many similarities to Nazanin’s: both arrested when on holiday visiting family, both targeted for their links to the UK, both had their jobs in London turned into cynical espionage claims.

Today they are cellmates in Evin prison. They often share a cup of tea, and talk about their lives in London, now so far away. Two weeks ago, Aras’s family had been told the verdict was being delayed, awaiting other considerations. We had shared their hope that she was not another political chess piece.

Iran jails Iranian British Council employee for spying for UK Read more

Then came Monday’s sentence – not told to a lawyer, but announced on TV: 10 years in prison. Iran’s revolutionary court convictions of foreigners are never about justice. They are advertising an imprisonment.

For my family, the announcement was also ominous.

There had been mixed signals with Nazanin’s case over the past two months – with a health commission proceeding in the background conducting tests that might lead to her medical release. Nazanin recently saw a psychiatrist – who was so shocked at her state, she recommended instant hospitalisation. There were hopes for Ramadan. Even a Persian lion from Bristol zoo had been sent to live in Tehran zoo, much to Gabriella’s excitement.

So this week’s renewed hostility from Iran came as a shock. Our family were told all those tests needed to be repeated, the hospitalisation was blocked. The judiciary again announced the opening of Nazanin’s second court case. What happened to provoke the change?

Nazanin and Aras are among many foreign and dual nationals and some permanent residents held on arbitrary cases by Iran. There are more than 30 known cases of foreign and dual national political prisoners from North America and Europe unfairly held in Iran since 2014 – most with outside links as academics or charity workers, working on the environment or culture, all framed with opaque “national security” cases.

Timeline Imprisonment of Nazanin Zaghari-Ratcliffe in Iran Show Hide Arrest in Tehran Nazanin Zaghari-Ratcliffe is arrested at Imam Khomeini airport as she is trying to return to Britain after a holiday visiting family with her daughter, Gabriella. Release campaign begins Her husband, Richard Radcliffe, delivers a letter to David Cameron in 10 Downing Street, demanding the government do more for her release. Sentenced She is sentenced to five years in jail. Her husband says the exact charges are still being kept a secret. Hunger strike Nazanin Zaghari-Ratcliffe's health deteriorates after she spends several days on hunger strike in protest at her imprisonment. Appeal fails Iran’s supreme court upholds her conviction. Boris Johnson intervenes Boris Johnson, then Foreign Secretary, tells a parliamentary select committee "When we look at what [she] was doing, she was simply teaching people journalism". Four days after his comments, Zaghari-Ratcliffe is returned to court, where his statement is cited in evidence against her. Her employers, the Thomson Reuters Foundation, deny that she has ever trained journalists, and her family maintain she was in Iran on holiday. Johnson is eventually forced to apologise for the "distress and anguish" his comments cause the family. Health concerns Her husband reveals that Zaghari-Ratcliffe has fears for her health after lumps had been found in her breasts that required an ultrasound scan, and that she was now “on the verge of a nervous breakdown”. Hunt meets husband New Foreign Secretary Jeremy Hunt meets with Richard Ratcliffe, and pledges "We will do everything we can to bring her home." Temporary release She is granted a temporary three-day release from prison. Hunger strike Zaghari-Ratcliffe is on hunger strike again, in protest at the withdrawal of her medical care. Diplomatic protection The foreign secretary, Jeremy Hunt, takes the unusual step of granting her diplomatic protection – a move that raises her case from a consular matter to the level of a dispute between the two states. Travel warning The UK upgrades its travel advice to British-Iranian dual nationals, for the first time advising against all travel to Iran. The advice also urges Iranian nationals living in the UK to exercise caution if they decide to travel to Iran. Hunger strike in London Richard Ratcliffe joins his wife in a new hunger strike campaign. He fasts outside the Iranian embassy in London as she begins a third hunger strike protest in prison. Hunger strike ends Zaghari-Ratcliffe ends her hunger strike by eating some breakfast. Her husband also ends his strike outside the embassy.

Moved to mental health ward According to her husband, Zaghari-Ratcliffe was moved from Evin prison to the mental ward of Imam Khomeini hospital, where Iran’s Revolutionary Guards have prevented relatives from contacting her. Daughter returns to London Zaghari-Ratcliffe's five year old daughter Gabriella, who has lived with her grandparents in Tehran and regularly visited her mother in jail over the last three years, returns to London in order to start school. Temporary release Amid the threat of the coronavirus pandemic, she is temporarily released from prison, but will be required to wear an ankle brace and not move more than 300 metres from her parents’ home. New charges Iranian state media reports that she will appear in court to face new and unspecified charges. In the end, a weekend court appearance on a new charge of waging propaganda against the state that could leave her incarcerated for another 10 years is postponed without warning, leading Zaghari-Ratcliffe to say "People should not underestimate the level of stress. People tell me to calm down. You don’t understand what it is like. Nothing is calm."

The cases have many common patterns: secret trials and refusal and threats to lawyers; the use of solitary confinement especially during interrogations; the prevention of outside consular access; the denial of medical treatment as a tool of pressure; the broadcast of smears on state TV; the raids and surveillance on the family home particularly if the families start campaigning.

These cases should not be seen simply as random and unconnected cases, but part of a new wave of hostage diplomacy. This is accelerating in Iran – though it is not unique. There is an increasing tendency of other states to arrest each others’ citizens to get their way in diplomatic spats.

With Iran, the UK has not been successful at challenging this practice, nor at addressing Iran’s underlying claims. Three years of quiet diplomacy has failed to deliver. But so too has the broad bellicose approach of others. For all the drumbeats and tweets, what has Donald Trump achieved for the US hostages in Iran? For all our energy deals, what has the UK achieved for ours?

What is needed is coordinated action. The plight of Nazanin over three years has taught me that systematic abuses are rarely solved by euphemism, but shared values and accountability. Two months ago Jeremy Hunt granted Nazanin diplomatic protection. This week shows it is now time to act.

Iran should realise jailing Nazanin Zaghari‑Ratcliffe harms its security | Simon Tisdall Read more

Next month the US president comes on a state visit to the UK. We will be asking Hunt to lead international coordination with like-minded states, at the UN security council and elsewhere, to reaffirm that we do not solve our problems by holding each others’ citizens hostage – there should be accountability for those who do.

This erosion of previous norms against state-sponsored hostage taking creates more than a protection gap for individual citizens. It risks allowing a new middle ages of international law.

It is important to increase the cost – for Iran and others – of holding innocent people as leverage. We need this before more people are quietly taken.

•Richard Ratcliffe is the husband of Nazanin Zaghari-Ratcliffe. He works as an accountant and lives in London