Today she reveals how the Yorkshire-raised terrorist begged her to join him in a London hotel the night before the attacks in 2005 – and told her he had a ‘surprise’ and a ‘treat’ in store for her the next day.

Nicki initially agreed to go with Lindsay and it was only a chance reunion with a long-lost friend that persuaded her to spend the evening elsewhere.’I am convinced he wanted to take me on that train that day,’ she says. ‘It has haunted me ever since.’

She also tells of how he flew into a furious rage after received a phone call now known to have been from July 7 plot leader Mohammed Sidique Khan giving him the go-ahead for the attack.

Just 17 at the time, the trainee chef was besotted with the ‘cheeky, genuine’ young man whom she met at a community centre in her home town of Aylesbury, Buckinghamshire.

Nicki, who left school at 15 to work a string of minimum-wage jobs, had barely ever left the Buckinghamshire town when she met Lindsay and says she had no inkling of his plans.

She admits she was painfully naive and, in person, comes across as straightforward but not someone who would necessarily think critically or ask difficult questions.

She witnessed behaviour – such as Lindsay asking her to get him a gun – that would have raised red flags for many but, having fallen in love, she sought to explain it away as him showing off.

Neither did she have any clue that he was married and his wife was expecting his second child, happily accepting that Lindsay was living with an ‘ex-partner’ a few streets from her home. Indeed, she only found about his wife, Samantha Lewthwaite, a British Muslim convert, from newspaper reports after his death.

For Nicki, the ‘happy-go-lucky guy’ was almost always calm and relaxed. ‘He was the perfect gentleman,’ she says. ‘He was polite and well spoken and would open car doors for me and always pay for everything.’

It is not an image of Britain’s deadliest suicide bomber that the 52 victims’ families will recognise in the week that an inquest verdict of unlawful killing gave them – at last – some hope of closure.

Nicki met Lindsay at a boxing club held in a community centre on the down-at-heel Quarrendon Estate in Aylesbury, where they both lived. He was an unemployed carpet-fitter with anger in his heart; she an impressionable 17-year-old who worked in a fish and chip shop. Both were looking for an escape.

She remembers: ‘I was there watching a friend’s 14-year-old son. But it was him who kept looking over at me while he was boxing. On a break he came over, winked and told me he was called Tyrone.’

IN THE car park, he flashed his muscular midriff at her while changing his shirt – then asked her out. An hour later, he took her in his red Fiat Brava to Watermead Lake in Aylesbury, where they talked for hours. ‘He was cheeky but he came across like a genuinely nice person.

He didn’t seem like the sort of guy who would be going out and getting himself in trouble like most lads his age would be.’

For a 17-year-old girl with limited horizons, it is not hard to see the attraction of this charming, well-built 19-year-old with his own car, a winning smile and plenty of cash in his wallet.

But the warning bells should already have been ringing. ‘He already knew my surname, my school and that I liked football and athletics,’ Nicki recalls. ‘I was puzzled but not really worried and I asked him how he knew this. He just laughed and said, “Don’t worry, I’ve done my research”.’

Neither did she probe Lindsay further when he told her his job was ‘writing songs for my dad’. Even now, it is unclear if this was a euphemism or simply a lie. How he had so much cash when he admitted to her that this songwriting was unpaid is another question that went unasked.

Soon Lindsay was picking her up every day in his car. ‘We went from being friends to being in a full-blown relationship,’ she reveals. ‘I loved him and he told me he loved me, often about 30 times a day. He didn’t seem aggressive, he didn’t lose his temper or swear. We never argued.’

But despite the ease with which he appeared to manipulate and deceive her, it seems that she held some power in the relationship. Nicki, who describes herself as ‘boisterous’, says she often teased the soon-to-be mass murderer.

She says: ‘I would push him away and play hard to get but he’d never get offended.’

Indeed, her dismissive attitude towards Lindsay even stretched into his most holy territory – religion. ‘At first he didn’t tell me he was a Muslim,’ she says. But on their third or fourth date she saw printouts of poems left on his dashboard in which the word ‘Jihad’ featured heavily.

‘He encouraged me to read them,’ she recalls. ‘But I’ve never been into religion and even now I don’t understand what the word means. After that he would go on and on about religion – once he told me that if he abided by Allah, he would be given 70 virgins in paradise.’

‘I just wasn’t interested,’ Nicki adds. ‘Mostly I wouldn’t listen or would just tell him to shut up. He was always telling me – ordering me, even- not to drink or smoke, but he never told me what to wear.’

Lindsay, who called Nicki his ‘cheeky princess’, seemed to let her defiance wash over him. According to Nicki, he never seemed fanatical and was into Western culture. His favourite music star was hip-hop artist 2Pac and he would always wear adidas or Nike tracksuits. If warning bells had not rung by this point, they definitely should have when – out of the blue – the Jamaican-born terrorist asked her if she could get him a gun, saying he was ‘having some trouble with my friends’. Even now, Nicki admits she had no idea what this meant.

Shocked, she refused and they drove home in uncomfortable silence. But almost inexplicably it did not cause her to raise her guard. She says: ‘I just thought he was just trying to be cocky and show off.’

Later, it was to emerge that when Lindsay’s car was found after the attacks parked at Luton station, it contained a semi-automatic pistol, bullets and a telescopic sight.

Nicki was present on June 25, a fortnight before the bombings, when Lindsay was given the go-ahead for the attack. Understandably, she was not to realise the significance of this call until later.

It came on a shopping trip to Milton Keynes, where he often took Nicki, apparently to reduce the chance of being spotted by his wife or anyone else who knew him. Nicki recalls: ‘That day we went to McDonald’s. Though he didn’t eat anything he didn’t seem to mind us eating there.

‘Some of my female friends were there and they later told me he spent £400 on perfume for my birthday on July 14. They thought it was a lot to spend, but he insisted, “No, I love her.”

‘Just after that we went to a shopping centre and he bought me a milkshake Then he got a phone call and walked away. When he came back it was the only time I saw him agitated. He just said we needed to leave. I argued with him then he swore, “Get in the f***ing car, we need to go.”‘

NICKI continued: ‘He was fuming. He drove back to Aylesbury like a nutter, way above the speed limit with music blaring out. I tried to talk to him and he just turned the music up louder when I opened my mouth. After that, he disappeared for four days and later told me he’d been writing songs in London.’

Phone records have shown that call was from July 7 ringleader Mohammed Sidique Khan, who himself had just received a call from Pakistan. Days later, on June 28, Lindsay went on a reconnaissance mission to London with Khan and fellow bomber Shehzad Tanweer.

Nicki says: ‘That trip really shook me up. It was the first time I had ever seen him not calm and relaxed. It was the first time I heard him swear. It was the only time I saw him speeding. I refused to text him for two days after that but then became so worried that I did – and even then he did not reply.’

Soon Lindsay was back in touch, however, to persuade her to stay with him in a London hotel on the night of July 6. She says: ‘I spoke to him on July 5 and he was really apologetic.

He said he would make it up to me by taking me to a hotel. He promised me there would a surprise or a treat he next day.’ She is convinced Lindsay meant for her to die with him that day – evidence, if it is possible, of an even more depraved mind than previously thought. It is something Nicki says she will never fully get over.

Later, he texted her: ‘I want to stay with you forever’ before adding: ‘Come on, it will be nice to spend some quality time together and we’ll have some bad boy room service.’ She agreed.

On the morning of July 6, she packed an overnight bag ready for the trip. But crucially, later that day, she ran into an old school friend she had not seen for four years.

Nicki says: ‘I ended up at her house in the late afternoon. I had taken my bag with me and Tyrone, as I still knew him, was meant to pick me up from there at 6pm. Then I had a few drinks and a good laugh with this good mate I hadn’t seen in years. She made me feel quite bad when I told her I was leaving so I stayed. I didn’t have the heart to leave her. So I spoke to him again and told him I wasn’t going to go. He wasn’t impressed but tried to gently persuade me.

‘I told him we could do something on my birthday a week later but he said, “I may be around then or I might not.”

‘He kept calling me back and after the last time I got off the phone to him, I got a text saying, “I love you more than you can imagine.” That was the last time I heard from him.’

Nicki stayed up late with her friend and slept through the initial reports that four bombs had ripped through three Tube trains and a bus between 8.50am and 9.47am on July 7. She remembers: ‘Once I saw it on the news, I was horrified by it all. I was close to tears. I was also worried about him. I didn’t know if he had still gone to London. It crossed my mind that he could have become a victim of it. So I kept calling his mobile but, of course, I got no answer.’

Nicki was not a regular newspaper reader and believes her friends were trying to keep the news from her – so it was not until July 17 that she saw Lindsay’s picture in a newspaper and realised he was a suicide bomber. ‘It made me feel sick to know that I was in a relationship with someone who can do that to any human being,’ she says. ‘He is beyond contempt and I can’t believe I ever fell in love with him.’

Nicki gave a statement to the police, parts of which were read to the 7/7 inquest earlier this year. The experience took its toll on her health. ‘For years afterwards I started getting pretty aggressive towards people, especially men. I was on anti-depressants for about 18 months and started drinking a lot. I wasn’t in a good place,’ she says.

‘I would just sit at home and think if there was anything I could have done to prevent it – to save all those lives. But I simply never had any clue of what he was up to.’

Lindsay’s widow, Samantha, who gave birth to his second child after the attacks, believes his ‘innocent, naive and simple’ mind was ‘poisoned’ by radicals. Nicki disagrees. ‘I don’t hold anything against his wife. But I don’t think he was brainwashed.

You could see straight away he was intelligent and thoughtful. Maybe he did get into the wrong crowd but that was no excuse. I think he knew exactly what he was doing.’

Nicki, who has since come out as a lesbian, is marrying partner Holly, 20, this summer and the pair are starting a new life on the Isle of Wight. ‘I hope I can put it all behind me now,’ she says. ‘He’s ruined enough lives – I’m not going to let him destroy mine as well.’

Additional reporting: Tom Hendry