‘What about it?’ asked Lady Ty who had probably been planning to hold my feet to the fire but now had something else to worry about – thank god.

‘Do you know its current whereabouts?’

‘George has a space at the car park at Marble Arch,’ she said. ‘He always leaves it there when he’s away working.’

‘A car matching its description was used to buy the drugs that killed Christina Chorley,’ I said.

‘That’s not possible,’ said Lady Ty and strode across the kitchen to where a surprisingly unbranded clutch bag was sitting on the counter beside the microwave. From it she pulled a set of keys and dangled them at me. ‘There are only two sets of keys,’ she said. ‘George has the others.’

‘Then it must have been you who drove down south to buy drugs,’ I said.

‘That’s absurd,’ she said. ‘You know that’s absurd.’

‘I have a dealer who can identify your car and I can prove that it was in the right place at the right time – I’ve got the CCTV,’ I said. Which was a total lie. At best there was a fifty-fifty chance that should I spend five days tracking down cameras I might find one that had recorded the event. ‘If it wasn’t you, who was it?’

‘I’ve told you,’ said Olivia from behind me. ‘It was me.’

‘Olivia can’t drive,’ said Lady Ty. ‘I offered to pay for lessons, but she can’t even be bothered to apply for a provisional licence.’

This I knew – just as I knew that Phoebe Beaumont-Jones had a brand spanking new driver’s licence, issued just a month previously. Obviously she was better motivated than our Olivia.

‘So it must be you,’ I said to Lady Ty, who raised an eyebrow in reply. I drew myself up and said in my most serious voice – ‘Cecelia Tyburn McAllister-Thames I—’ It’s a long name and I drew it out as much as I could, but you’ve got to wonder what might have happened had Olivia been made of sterner stuff.

‘Fine,’ said Olivia. ‘Fine, okay, I wasn’t alone.’

Lady Ty met my eyes before I turned to face her daughter, and her gaze was cool and ironic and terrifying.

‘Was it Phoebe?’ I asked.

‘Yes,’ said Olivia.

‘Did she buy the drugs?’ I asked.

Olivia hesitated.

‘Did she?’ said her mother.

‘Yes.’

Lady Ty asked if buying the drugs had been Phoebe’s idea and, when Olivia hesitated again, asked the question again in a tone I recognised from my own mum. The one that says: Yes there’s going to be trouble, but that is as nothing to the trouble you are about to be in if you continue to cross me.