Much of the afternoon was taken up with meetings and repetitive discussions about the Operation Tresco submission. Tresco was an operation against the Islamic State group in Syria aimed at identifying and, where legally permissible, capturing or killing senior leaders and any others thought to pose a threat to the UK. The main penetration agent, a British-based Afghan codenamed Herm, had got alongside a major target, Tresco/1, a Birmingham-born Briton of Pakistani origin who had joined al-Qaeda before transferring to IS, where he now trained others like himself to return to the UK and kill people. As well as training those on the ground, he provided Internet coaching to so-called lone wolves resident within the UK. One had recently driven a car into a group of Liverpool football supporters, killing one and injuring three. He was armed with two knives and had been arrested at the scene by police using tasers. Meanwhile, in Syria Herm had made contact with Tresco/1 at the flaying and execution of suspected spies. Herm’s knowledge of Britain led to his being instructed to help with training. The aim of the operation was for Herm to plant a guidance device on Tresco/1 that could be used in a drone attack.

Submissions that could lead to a killing had to be approved by the prime minister and the to-ing and fro-ing of the afternoon between MI6 legal advisors, Foreign Office legal advisors, Number Ten and the MOD had concerned whether the wording required for legal conformity properly matched the facts as known. During moments when he was alone with his screen Charles would turn away and gaze out of his window towards the Embankment and the Thames, finding that in the opacity of the stretch of water he could glimpse something that lifted his thoughts from the immediate. That had been the essence of his passion for fishing when he was a boy; not so much the fish he caught as the solitude and mystery of being by water, the lure of the unseen. Now, musing on what they were doing, he wondered whether he lacked moral concern. Everyone else involved in the Tresco submission seemed morally satisfied, their concern being to demonstrate legal conformity rather than ethical rightness. Anyone with qualms could ask to be assigned to other work, or transfer out. Not that the killing of a killer troubled Charles. He had done it himself. Doing it remotely via a drone seemed morally no different from killing with a sniper rifle, which in the case of Tresco/1 he would have been happy to do.