‘That’s what that colour is called – Imperial Blue,’ said Aiden.

‘Can you remember what she was wearing?’

‘No, mate. Sorry.’

Which is a good demonstration of why eyewitnesses have all been a caution since Marc Anthony said ‘I dunno mate, they were all wearing togas.’

‘Did you notice the year on the plate?’ I asked.

‘Yeah,’ he said. ‘It was a 63.’ But crucially he didn’t remember the area code or the rest of the index. Some things are more important to some people than they are to others. 63 meant the car was registered between September 2013 and February 2014 – which might narrow it down a bit.

I terminated the interview and gave him back to Bromley CID and told them what a good boy he’d been – for whatever good that might do him. Then I headed back across the river and settled back at my corner of the desk at Belgravia nick. Carey grumbled and shifted over, but he was too busy doing the metric ton of paperwork involved in organising a raid to chat. Guleed was out – presumably still terrorising the sixth form at St Paul’s.

As soon as Aiden Burghley had mentioned the blue BMW, there’d been a little tickle in my brain. And when I logged into HOLMES and a did a word search through the Marigold nominals there it was – a blue 63 reg BMW X5 registered to George Thames-McAllister. On the off-chance I ran an ANPR sweep on Bromley and there was the right BMW, tooling down the A21 towards the town centre and then back again. Exactly the right time window for Aiden Burghley to sell its occupant some MDMA.

I hesitated before I added this to HOLMES – I didn’t want to firm up the case against Lady Ty’s wayward daughter, but the whole point of a collation system is that you feed in information to collate. Still, with her mother’s influence putting the brakes on the investigation I figured that Olivia was safe for the moment. With a bit of luck that would give me time to sort things out using the time-honoured tradition of exploiting family connections.

In days of old, a stout yeoman would set out from Aldgate along the road to Colchester in the full knowledge that just a mile up the road was a small hamlet where he could stop for a pint and a cheeky pie. This rest stop was called Mile End from Le Mille End which is your Norman French for a hamlet a mile up the road. The road from Aldersgate was called Aldgatestrete and then, because that was considered too on the nose, the Mile End Road. It’s where young Richard II signed the peasants’ charter with his fingers crossed behind his back and the first ever V1 cruise missile to land in London hit. It’s also where Queen Mary University teaches Environmental Science, so it was there that I had lunch with Beverley Brook.