Downing Street’s aura of urgency blended with sedateness never grew stale for Tennant. There was something tangible about the echoes of the past in these rooms. Was that a chair where Clement Attlee liked to sit? Was this a carpet that Lloyd George trod on? The PM’s chief political adviser, a towering man with a close-shaved head, beckoned the waiting group into the office. Tennant pulled out his mobile, switched it off and left it in a cubbyhole by the door, then walked into the brightly lit room with white-panelled walls and surprisingly pungent vanilla air freshener.

The PM, grey-haired and grey-faced, rose from his antique desk to shake hands. On television, he came across as a slight man. Tennant had been surprised to discover on his first meeting that he was six foot three and filled rooms. And not just with his physical size.

‘Apologies for the stench – Rupert had an accident in here earlier,’ he said as he waved them to the mahogany conference table. For a second, Tennant was flummoxed. The PM didn’t do jokes. Surely, he didn’t mean Rupert Sealy, the Education Minister?

The Home Secretary Ben Thomas, a big Geordie whose warm smile lay below cautious, watchful eyes, was already sat at the table. He nodded at Tennant as they settled down.

‘Same problem with my Labradoodle Edward – good as gold normally, then eats some crap and, bang, new carpet time,’ said Thomas.

Ah, thought Tennant with some relief. Rupert was the PM’s Cocker Spaniel, an animal who had become a minor celebrity in the last few weeks after the Downing Street cat had taken a swipe at him on the doorstep.

The PM nodded to Tennant. No jokes, he told himself, no smart asides, just a massive dump of content. Not unlike Rupert.

He summarised the casualty figures and gave an update on the hunt for Gareth Fletcher.

‘This Fletcher,’ said the Home Secretary. ‘Are you taking seriously his claim that he’s with the NRF?’

Tennant shrugged. ‘Nothing’s ruled out, Home Secretary. For now, we have to chase every line. When the NRF were proscribed by your predecessor, we had intel they had the intent to commit attacks and were trying to build capacity. It’s possible they’ve achieved that.’

The Prime Minister turned to the head of MI5. ‘How good is your infiltration of the NRF?’

‘Could be better, Prime Minister,’ she said. ‘They’re relatively new, we’ve got agents only at low levels and we don’t have much on the new leadership. It’s a priority for us, of course. Along with all the other priorities,’ she added more quietly.

Tennant paused, sucked on his front teeth, and decided to take a gamble. ‘There is also concern by some senior officers about the NRF video. It could be interpreted as the opening salvo in a new sustained campaign of terror by this group. We have been warning about the rise of the extreme far right for some considerable time.’

The Home Secretary tutted and fidgeted in his seat. ‘I’m sorry, Steven, but what worries me more right now is the backlash from the Muslim community, not the imagined response of the far right.’ He leant across the table towards the Prime Minister and jabbed a finger on its surface. ‘There will be reprisals. Ishmail Sherif has already been on Twitter whipping things up.’