The young couple who moved into St Agatha’s Road in Birmingham seemed as ordinary as the net curtains hanging in the windows of their modest terrace or the red Ford Fiesta parked outside.

Each morning, they would leave the house together in the Fiesta. He was always dressed in a suit and would drop off his wife at a nearby children’s nursery, where she was an administrator, before continuing the short journey to the family-run accountancy firm where he had been employed since leaving college.

Everyone agreed that newlyweds Ummariyat Mirza and heavily pregnant Madihah Taheer were a welcome addition to the street popular with young families. Neighbours remember the young woman beaming with pride when other mums commented on her baby bump.

Birmingham’s links with Islamic militancy and terrorism in recent years have overshadowed the positive contribution made by the Muslim community to Britain’s second city.

But these childhood sweethearts, both 20 when they married in 2016, never aroused suspicion. They weren’t especially religious; neither of them prayed at the local mosque — which is not to suggest there would have been anything wrong in this. More that, to the outside world at least, they appeared to have fully embraced a very ordinary, British way of life.

Terror threat: Unmariyat Mirza, left, and Madihah Taheer were plotting a massacre

The only outward trappings of their Pakistani heritage was Taheer’s headscarf — never a burka — which left her face uncovered. Indeed, while at school she didn’t even wear a headscarf. Contemporaries recall how she and a friend once performed a rendition of Rihanna’s hit song Umbrella. Yet their seemingly normal Brummie life was a lie; a sham even before they were joined together in matrimony in an Islamic ceremony which had no basis in British law.

British? The reality was that the couple hated this country and everything it stood for; even though both their families, originally from Pakistan, brought up nine children between them here and Taheer herself benefited from one of the best educations Birmingham could offer.

The truth, despite the exterior, was that this husband and wife were more ‘Mr and Mrs Jihadi’ than any sort of besotted lovers.

Behind those net curtains in St Agatha’s Road was perhaps the most grotesque manifestation of the couple’s true feelings.

It was a life-sized dummy with slash marks across the forehead, throat and abdomen, the result of sickening training sessions when Mirza used a plastic martial arts training knife to practise killing and maiming ‘infidels’ — non-Muslims.

A real hunting knife, purchased by the wife and wielded by the husband, would have been used in the actual terrorist attack they were planning, had he not been arrested.

Detectives found a number of possible targets on the couple’s home computer. Internet searches on Google included ‘barracks in Birmingham’ and ‘Territorial Army in Birmingham’, as well as lists of Jewish communities in Birmingham and London and searches for Islamic State (ISIS) propaganda videos featuring beheadings and torture.

Unmariyat Mirza posing with a rifle

Experts say that in criminal partnerships there is often someone who leads and someone who follows. It would be all too easy to stereotype pretty brunette Taheer in the role of the follower. But although her future husband may have initially been the driving force for the plot, she became an enthusiastic participant.

This is apparent from the text messages they swapped shortly before their marriage, in which he called her ‘the perfect partner and soulja (soldier)’ and ‘soulmate’.

And in the eyes of the law they were equally culpable: Madihah Taheer was convicted of preparing an act of terrorism at Woolwich Crown Court last week, a charge her husband had admitted earlier. They will be sentenced next month.

Exposed though they might have been, their trial raises a disturbing question: how many other so-called ‘Mr and Mrs Jihadis’ like them are concealed in our midst?

A number of similar cases are going through the courts and a string of others have already made headlines recently, including the magistrate’s daughter from Reading who encouraged her husband to launch a suicide attack on the anniversary of the 7/7 bombings, and newly-weds from Oldham who were preparing to murder members of the local Jewish community within months of meeting on an internet dating site.

So this Birmingham-based terror plot, which was thwarted days after the Westminster atrocity in March, is far from an isolated scenario. Nor is it a new phenomenon.

Recall that the wife of one of London’s failed July 21 bombers was jailed for ten years for helping her husband. She delivered tapes of extremist preachers to one of his friends as a ‘bequest’ on the evening before the attacks in 2005, which could have caused similar carnage on the Tube and bus network as the July 7 outrage two weeks earlier.

More than this, it’s likely the threat from such husband and wife pairings, intent on pursuing jihad here, is set only to increase with the collapse of ISIS territory in Syria and Iraq.

More than 400 of the 850 Britons who left to join the self-styled caliphate during the past five years are now believed to have returned home. But as few as one in eight of these jihadists have been prosecuted, the latest Home Office figures reveal, and there are fears many have simply ‘disappeared’ from the view of the security services.

How many of them, if any, were couples or have since become couples? Whatever the truth, recent events prove that ‘marriage’ can provide a convenient cover for the new terrorist plots facing Britain.

The two protagonists of this latest story were at separate sixth form colleges in Birmingham when they met, through mutual friends, and started dating. He was 16. She 17.

Madihah Taheer with a gun in an image posted online

Their journey from apparently normal teenagers to murderous fanatics in the space of a few years is truly disturbing. They had barely reached adulthood when the mannequin was installed in their house for Mirza to hone his deadly stabbing technique. His wife also filmed herself striking the dummy violently in the neck and chest, it emerged in court.

Few Muslim girls, however, could have been more Westernised than Madihah Taheer. Both her mother and father, a one-time railway supervisor who now works in a warehouse, were born in Birmingham.

The second of four sisters, Madi, as she was known, went to Thornton Primary, one of the city’s most popular infant schools which attracts almost seven applications for each place. ‘Madi was one of the cleverest in the school,’ said her best friend at the time. ‘She was put into a special class as one of the high performers who needed more stimulation.

‘She wasn’t obviously Muslim. She was into pop music and just normal stuff. At the leavers’ do, we did dance together to Rihanna’s Umbrella. We stayed in contact for a couple of years and then lost touch.’

The young woman, who is now facing a future behind bars, fulfilled her early academic promise, and later studied at Hodge Hill Girls’ School, achieving top GCSE grades.

Not long afterwards she started a small online business selling personal items such as Harry Potter books, jewellery, handbags, shoes and clothes. A photograph of each item appeared next to the modest asking price. One such list from about four or five years ago is still online and offers a glimpse of the normal girl Madihah Taheer once was:

Black vintage clutch (‘Good condition/gold buckle detail. Every girl needs the perfect black clutch’); Leather jacket with hood (‘Comfy, good material. Worn, but looks new’); Never-worn heels (‘Open to offers’); Chalcot Crescent by Fay Weldon (‘A quirky, humorous and cleverly written book’).

Like his future wife, Mirza came from a big family. His father owned a restaurant, and it has now been revealed that an older sister, Zainub, 23, is also awaiting sentencing after pleading guilty to sending him a series of explicit Isis videos. One of five children, he went to Saltley School, now an academy, which perhaps offers a clue to the path he would later follow.

Police image of a replica gun Taheer played with

Saltley was engulfed in the Trojan Horse storm, when radical Muslims attempted to take over state schools and run them on strict Islamic lines. Mirza’s former headmaster was ousted by hardline Muslim governors.

At one time, Mirza lived in Alum Rock Road in Washwood Heath, which could also be significant. For one in ten of all Britain’s Islamic terrorists, according to a report this year, have come from just five neighbourhoods in Birmingham. One of the neighbourhoods in question is Washwood Heath.

Outwardly, like his future wife, Mirza showed no obvious signs of radicalisation. Someone who remembers him from those days says his main interest was ‘training’ and mixed martial arts; he was a fan of Bear Grylls, the TV adventurer and survival specialist.

Taheer was specifically asked in court if her then boyfriend was interested in jihad when they met. ‘Not at that stage, no,’ she replied. But she said their relationship distracted her from her studies and she failed her A-Levels, ending up working in a children’s nursery after a higher education course.

He joined accountancy firm Meer & Co, based in Birmingham, which is run by a member of Mirza’s extended family.‘I would see him most mornings when I took my kids to school and he was always smiling and saying hello,’ one neighbour said of Mirza.

She was talkative, a nice young lady,’ another neighbour said of Taheer. You would have had to be a mind reader to have been aware of the transformation that was taking place beneath the surface. By the time she gave birth in May this year, Taheer would be on bail and her husband on remand. From the witness box at Woolwich Crown Court, Taheer said that her husband felt an ‘emotional attachment’ to ISIS. ‘For me, as well,’ she admitted.

‘He thought what they [ISIS] were doing was beneficial,’ she said. ‘He told me to download a Twitter account where we would keep up to date with the conflict in the Middle East... That’s where I was introduced to IS... It started as something I would humour him with, but as things [in Syria] got worse, I was sucked into it.’

But the jury did not believe that she was simply a naive young woman who was groomed for jihad by her more fanatical husband.

After all, it was she who bought the ‘training dummy’ and the ‘murder weapon’. The pair had hoped to travel to Syria to help ISIS but decided to carry out an atrocity in Birmingham instead. The jury was shown hundreds of text conversations from the couple’s courtship onwards. They provide a frightening insight into the mindset of homegrown jihadists.

In messages to each other, Mirza said he wanted to stab someone 27 times, to which she replied that ‘sounds so satisfying’.

In one exchange several months before they married, Taheer told him she needed a brave husband to kill for her: ‘Can we get married already ffs [for f***’s sake],’ she asked rhetorically. ‘I want you to kill for me, I have a list.’

The list included the name of MailOnline columnist Katie Hopkins (‘the biggest kuthi [bitch] of them all’).

He replied: ‘The day of nikkah [marriage] I’ll kill ’em all. Give me the list. The only thing that stops me is that we are not married.’

The couple took turns to boast about who was the most committed to jihad, with Taheer taunting Mirza as ‘Mr Moderate’. There were also occasions when the outrageous dialogue resembled the Four Lions film, a satire about four incompetent British jihadists, like the time the couple wondered if IS would be able to perform laser eye surgery to correct Taheer’s faltering eyesight. After an eye appointment, she told him: ‘I won’t be able to get laser for at least another year, maybe two.’

‘Okay u may as well just get surgery in jannah [paradise]’, he replied.

The farcical exchange contrasted dramatically with the disturbing material found on their computer at St Agatha’s Road which showed IS hostages being burned alive, drowned in a tanks of water, and hung upside down on meat hooks with their throats slit.

Police eventually arrested Mirza in rush-hour traffic in March amid fears the couple’s attack plot was coming to fruition.

Inside that nondescript red Fiesta was a man consumed with desire to kill and wage jihad. Behind the walls of his neat house a few miles away, was his wife who, the courts agree, was as driven to do so as he was. One can only wonder how many other seemingly ordinary couples, plotting terror, are living all around us.