The 25-year-old, real name Sirach Charles, stroked it almost absent-mindedly as he reflected on the eight months he spent on remand awaiting trial for offences including firearm possession and robbery. "The number will always remain in my heart," he said. "It's a reminder of what could have been, the chapter that was the most challenging of my life."
The singer, songwriter and record producer has, until now, done a good job of keeping his skeletons hidden. He has brushed off questions about his past, refusing to elaborate on his time in jail or even to talk about the charges against him. But on the eve of the launch of his debut album, About Time, on which he collaborated with Grammy award winner Frank Ocean and lyricist George the Poet, he decided he wanted to open up for the first time. His motivation, he said, was to inspire others and show there is hope even for those who find themselves on the wrong side of the law.
He was, by his own admission, going down a bad path, hanging out with the crowd he "grew up with, not even a gang, it was just friends". Although he hadn't been in trouble with the police, he had had his problems. In year 8 he was expelled from his secondary school, Phoenix High in west London, for being disruptive in class, and was sent to a pupil referral unit.
By his mid-teens he had begun to covet things – the expensive watches, designer clothes, the newest trainers – and had decided he would do "anything necessary to get them". When I asked what he meant, his almond-shaped eyes narrowed."There's only one or two things you can do [to make money]. You can do drug dealing, you can do theft – which I would never dream of doing – or robbery, which I would never do. I would never do anything to harm anyone, but I was making ends meet. Any means necessary within my comfort zone."
The story is depressingly familiar, but in Angel's case the script was somewhat different. Far from being the product of a broken home or coming from a crime-ridden council estate, he grew up with his parents in a loving family in a four-bedroom terrace house not far from BBC Television Centre.
He was passionate about music from a young age, teaching himself to play piano, guitar and drums at home and composing tracks in the recording studio in the basement. His father, Tendai Charles, was a session musician who played with Bob Marley. When he thought his five children were old enough, he put them into a band which he called the Charles Family, co-managing them with the late reggae singer Smiley Culture. Their quest for fame was captured in the BBC documentary One Life, but despite the exposure success proved elusive. Angel continued writing songs and making music at home until "something crazy" happened. "We were out one night chilling, someone took my phone, said they were just going up the road." Then, the something crazy: a robbery involving a gun and an attempted kidnapping. Angel became embroiled after his phone and one of his bandanas was found close to the scene of the crime.
Police stormed his parents' home at 1am and by the following morning he was told by a judge that he was being remanded to Feltham. The gravity of what had happened only sunk in when he walked through the prison's huge metal entrance doors. "I remember them saying this is your prison number," he recalled. "I'm thinking: 'Prison number? I don't need that, why are you giving me that, I haven't done anything wrong.' I couldn't believe what was happening."
He stopped himself from becoming depressed in the eight months he spent awaiting trial by throwing himself into his music. He wrote several albums worth of songs in his cell, including the Pixie Lott and Jason Derulo track I'm Coming Home and several others that made it on to About Time. Prison was a wake-up call. He talked of "the will of God" and fate and reckoned that prison was the making of him. "Everything is written," he said. "Going away allowed me to think about what I was doing with my life. It made me realise you can get drawn in by association."