Stephen Holm was a senior analyst at the Joint Terrorism Analysis Centre. Part of MI5, its role was to sift through intelligence and assess the threat level posed by various groups and individuals. Holm’s route into JTAC had been circuitous. He’d started his career as a beat bobby on the Met before moving to CID where he’d been attached to Special Branch. He’d joined Special Branch long before 9/11, when the word terrorist invariably referred to the Northern Irish situation. That had been a dirty war, but the enemy had been familiar. They had the same colour skin, worshipped the same God and spoke the same language. They understood there were certain rules both sides had to abide by. If 9/11 changed that cosy view forever then the British equivalent – 7/7 – brought it to the streets of London with a literal bang. JTAC had been formed in the aftermath of 9/11 as the security services realised they were way behind the curve, and Holm had moved across from the police to Five around then, taking up a position in international counter-terrorism. His assignment to JTAC had come at fifty, and in the intervening years JTAC had had many successes and a few failures, but nobody kidded themselves the war was even close to being won.

No, Holm thought to himself, not even close.

There’d been whispers of a possible attack earlier in the week. Some vague intercepts from GCHQ. A person of interest making an unscheduled journey. A word from Palmer that he’d picked up a nugget from a deep-cover contact in Belgium. All these things suggested something might be about to happen, yet none pointed to an exact target or date. Nevertheless, Holm had a gut feeling of impending disaster but – as he often said to junior colleagues – you couldn’t go to the Spider and offer her a mere hunch. You needed a juicy morsel if you wanted her to bite.

He’d scuttled round all week trying to extract information from various sources, even tapping an informant he usually reserved for times when an attack was believed to be imminent. The informant, bribed with a cup of sweet black coffee and a fifty-pound donation to a local homeless charity, had mentioned a mosque he’d attended in west London. There’d been a visiting cleric from Palestine. A meeting of a youth group where pictures of atrocities committed by UK, American and Israeli forces had been passed round. Talk afterwards.

‘Hotheads and idiots,’ the informant, a moderate who had no truck with extremism, said as he bent to sip his coffee. ‘You want their names?’