I’ve been walking while we talk, down St James’s Street towards Pall Mall, where the confidence of Queen Victoria’s imperial Britain is manifest in the serried row of overbearing gentlemen’s clubs. It’s where Sherlock met Mycroft. Which sparks a thought.

‘Do you think they could have been spooks?’

An intake of breath. ‘We’ve discussed this before, boss. Just because Kendall was Home Secretary, that is not evidence.’

‘But he worked with them for years.’

The walk, and Jess’s news, has focused my thoughts. I’ve let myself be sidetracked. I’ve been so busy trying to track down Muller, and been so bullied by Breitner and Streatham, I’ve neglected my prime suspect.

‘Whatever Muller said to Kendall in their meeting, whoever he was acting for, it was still Kendall who made the decision to ditch the tax raid. He’s at the centre. Everything comes back to him.’

I pause, waiting for Jess’s inevitable objections, coolly ticking off the reasons I’m probably wrong. All I hear is breathing.

‘I don’t need Muller to tell me what he said to Kendall,’ I continue. ‘I just need to find out what he’s got on him.’

‘Why is Kendall any more likely to tell you than Muller? He’s got more reason to hide it than anyone. And he’s already told you to fuck off.’

‘I’m not going to ask Kendall.’

‘Who, then?’

‘Who do you think?’

Jess and I have been working together so long, we instinctively know the other’s next moves. ‘That’s risky, boss.’

‘There’s nowhere else to go.’ A grumbling cranking engine is approaching from behind. I stick out my hand to flag down the black cab. ‘I’ll call you back in a bit.’

The taxi pulls up and the driver rolls down his window. ‘Where to, young man?’

‘Breitner House, please.’

*

Breitner House is a modern pyramid of gold-tinted glass rising out of south London docklands. It’s one of those areas where all the ages of London are sandwiched together cheek by jowl: New York-style loft apartments in converted Dickensian warehouses; 1930s council estates that are the last fortresses of a white working class which has mostly fled north and east to suburbia; Tower Bridge looming in the background and the river flowing only fifty yards away. Four centuries ago, Shakespeare’s Globe theatre stood a few hundred yards to the west and soon it will again: you can see scaffolding surrounding faux-Tudor half-timbering, where an American actor is building a replica.