‘Hello,’ I said. ‘Obviously the cleaning gigs are paying well.’

Guleed asked if I knew her.

One thing you acquire as police is a good memory for names and faces, not only because of the long parade of villains you encounter but also because most of them are repeat offenders. It’s considered bad form not to know someone’s name when you’re arresting them for the fourth time. I’d met this one while raiding a County Gard office near Liverpool Street the year before. Just before I was distracted by the whole being on the roof of a tower block when it was demolished thing.

‘She gave her name as Awa Shambir,’ I said.

‘I seriously doubt that,’ said Guleed and then spoke to the woman in a language I assumed was Somali or a dialect thereof.

The woman kept her face down but I could tell she was smiling.

‘You couldn’t repeat that, but a smidge slower,’ she said. ‘I’m a little rusty.’

‘Not Somali,’ said Guleed. ‘Ethiopian maybe.’

Pure Home Counties, I thought, with a side order of posh school. Not the accent she’d used to talk to me when we last met.

‘What’s your real name?’ I asked, but the woman kept her head down and refused to speak. Nightingale and I left her with Guleed and retreated into the café for a quick bit of post incident assessment.

‘There are undoubtedly going to be consequences,’ he said. Which was Nightingale for: Look out, here comes the shit avalanche. ‘We need to make good use of our available time.’

We decided that I would stay with our mysterious not-Somali and bang her up in one of the special cells back at Belgravia.

‘Be careful,’ said Nightingale. ‘I didn’t recognise the formae per se, but her technique was very clean – I’d say she’s been training for a long time.’

I asked how long.

‘Difficult to say,’ he said. ‘But since she was a child for certain. Stay behind her and keep your hand on the cuffs.’ During the war, the Folly had developed techniques for dealing with captured practitioners – Nightingale had dusted off an old manual, I kid you not, complete with cheap khaki cardboard covers and line drawings. Basically it amounted to keep an eye on them and don’t let them get anything started.

‘I don’t think she’s going to be very co-operative,’ I said.

‘You don’t get that well trained without a master,’ said Nightingale. ‘Let’s keep her under lock and key and see who comes to fetch her.’

So while Nightingale and Stephanopoulos stayed to face the music, me and Guleed took our prisoner and legged it back to Belgravia to see whether a Sith lord turned up to bail her out.

The custody sergeant gave us a strange look when we booked her in.