She walked through the entrance just next to Downing Street and swung right to go down the stairs past the carefully preserved Tudor remnants of the palace that had stood there in Henry VIII’s time. She handed her phone in to the guard sitting by the security portals at the bottom. Her pass didn’t give her automatic clearance, so she waited for him to check her details against the names on the list, then open the door for her. She glanced through to the anteroom, where the more junior aides sat, sifting any last-minute intelligence coming in.

The prime minister, James Ryan, was already seated in the Cabinet Office Briefing Room, the setting for all Cobra meetings, waiting for everyone else to arrive, a very different approach from his predecessor, who had always liked to arrive last, preferably having kept his audience waiting. The PM was fifty-five, the same age as C, of whom he had been an exact contemporary at public school. He had the carefully cultivated crumpled air of the truly vain. His shirt did not appear to have been ironed and his thick, wavy dark hair seemed not to have seen a brush for days, giving him the appearance of a student who’d just crawled out of bed. He’d put on weight since crossing the threshold to Downing Street, his once handsome features now puffed and jowly. But he still liked to share his legendary charisma with anyone in his orbit.

‘Kate Henderson, as I live and breathe. What a pleasure to see you.’ He gave her a beaming smile.

‘Good morning, Prime Minister.’

‘Is it? I’ve been up for hours. It feels like lunchtime.’ He glanced at the cabinet secretary, who sat beside him. She was a tall, grey-haired, mostly serious woman called Shirley Grove, who, it was said, occasionally exhibited a flash of supremely dry and rather cutting humour. She didn’t find her boss funny in the least. ‘Must be why I’m getting so fat,’ the prime minister went on. ‘I keep inventing extra meals.’ He leant forward on the table and fixed Kate with a steely, half-amused gaze that was another of his stocks in trade, as if life was one long P. G. Wodehouse story. ‘How are you, Kate?’

‘I’m well, Prime Minister.’

‘Sorry to hear about your husband. Sounds like a wretched fellow. Better luck next time. That’s my motto.’ He smiled again. His latest girlfriend had just departed Downing Street after what was said to have been another tempestuous row. ‘I’m on the market,’ he had quipped at a recent dinner.

Kate coloured. She couldn’t think of anyone else tactless enough to make a joke of the breakdown of her marriage. But she was saved further embarrassment by Sir Alan’s arrival, which chilled the air by several degrees. He nodded at the prime minister and sat at the far end of the table from him, as if deliberately trying to keep his distance. The two men were said by contemporaries to have been close friends at school, but, if so, Kate had yet to identify the cause of the current hostility between them. He was followed by the defence secretary as the room quickly filled. The foreign secretary, Meg Simpson, and her senior team were the last to arrive.