Gabriel reread the report from digital forensics with growing frustration. Fletcher’s phone was a recent model and while forensics were confident they could hack it, it would take up to twenty-four hours. Her concerns about a follow-up NRF attack were as strong as ever and a day’s delay could make all the difference.

Gabriel dropped her bag and coat on the floor of her desk and sat down rather too heavily, dislodging the mechanism that kept the chair back upright and sending her coffee over the desk. She fiddled around with the levers, conscious that her failure to work a chair was being watched from outside her glass office.

‘Ma’am.’ Bose stood at the door, her round face and brown eyes creased with mild amusement. ‘Ready to go through?’ Gabriel nodded and followed her into one of the conference rooms overlooking the tower of St Pancras station.

Gabriel had worked with Bose for two years. She had never believed in first impressions – and Bose was an example why. On their first meeting, Gabriel had barely noticed the short, slightly overweight woman in her forties in the corner. Bose tended to get overlooked – not helped by her conservative dark suits and subdued voice. But within weeks, Gabriel had singled her out as one of the stars of her team.

Every SO15 team needed a broad palette of skills and specialisms and while someone like Neville Skeffington was happiest getting his hands dirty on the doorstep, Bose thrived behind a desk. Not only was she a formidable expert on returners – the British Islamists who had set off to the Middle East to fight for ISIS and were now slinking back to the UK – she had a good grasp of the extreme right.

Around one hundred officers were packed into the room, some on chairs, others standing around the edges. Skeffington, long and lanky, was leaning against the back wall, scratching the moustache under his aquiline nose with the end of a long finger as he whispered to a bored DC next to him.

‘First, the NRF,’ said Bose, from the central chair. ‘They broke away four years ago from England For The English, purported to be about peaceful protest, then moved to hate propaganda, generally against immigrants and Muslims. They graduated to advocating violence, were proscribed by the Home Secretary eighteen months ago. Their leader got sent to prison and the forty to fifty known members, a ragbag collection of oddballs and a significant number of ex-squaddies, seemed to fragment.

‘On to Fletcher. A record for petty violence. Held a job as a clerk in an insurance firm, colleagues say he was shy around women, resented being overlooked for promotion and was disciplined for offensive comments about a black footballer. No military connection. No known girlfriend or boyfriend. On to the video.’

The NRF video, downloaded from the internet, appeared on the screen behind her. She froze the image.

‘The trident symbol here,’ she pointed to the drawing behind Fletcher, ‘is a runic symbol – the life rune – appropriated by the Nazis in the thirties. Fletcher’s had the numbers eight eight tattooed on his left shoulder. It’s code for HH – or Heil Hitler – H being the eighth letter of the alphabet. Again, we see it used by white supremacists globally. Similarly, the one eight here stands for AH, Adolf Hitler. The one four isn’t a code – it’s a reference to the fourteen words in the rallying slogan for white supremacists, which Fletcher repeats at the end of his speech: “we must secure the existence of our people and a future for white children”. Finally, the blurred letters on the wall appear to be RAHOWA, which stands for racial holy war.