While the female officer directs traffic around us, I go to look at how bad it is. The frame looks as though it’s been crushed between the thumb and forefinger of some kind of Gogmagog. My car is a write-off. It’s a miracle I got out. Thank you Clare, thank you Clare, thank you Clare, I whisper.

‘What’s that?’ the policeman asks. I shake my head.

‘Tell me what happened,’ he pursues.

I describe ‘the accident’ but in the telling I cannot escape the terrifying idea that this was intended; that someone was trying to squash me. I look towards Whitehall, as if the driver might feel remorse and come back to apologise. ‘He drove off. Do you think there’s any chance you’ll find him?’

The female says, ‘Leaving the scene after a collision is a crime under the Road Traffic Act. We’ll do our best. Did you get his number plate?’

‘I was in no state to write it down. But the lady in the Volkswagen might have done.’

‘Which lady in the Volkswagen?’

I look around, expecting her to be parked behind me. But she and her car are gone. While I’ve been speaking to the police, she drove away. And she’s taken my notebook and pen. ‘That’s odd. She was the only proper witness.’

The woman officer gives me what feels like a pitying look.

‘I’m afraid you can’t leave the car here, sir,’ she says. Traffic is backing up behind me, to the National Portrait Gallery.

I tell her about my grace-and-favour parking space, just a few yards away, down the Mall. ‘Do you think it’s driveable?’ I ask.

The policeman prods the tyre doubtfully with the toe of his boot. ‘Not sure you should start the engine. But if you release the handbrake we can try to push it.’

I nod and climb in to the passenger seat. I am going to have to steer from here. The police have asked a couple of bystanders to help. The male officer asks me to release the handbrake and I lean to the right and take hold of the steering wheel. I can just about control the direction of travel. And with the woman officer guiding the traffic around us, we roll slowly down Trafalgar Square.

She gets into her car and turns on the warning lights, to follow us and protect us. With my police escort, I am travelling exactly the route that either Todd or Ramsey will take, also flanked by outriders, after the election in just a few days, when they’ll journey to the Palace to ask the Queen for permission to form a government. Our more eccentric cortège trundles under Admiralty Arch and down the majestic Mall. The roped-off car park, just by the dazzling white of the Institute of Contemporary Arts, is in view.