‘It all feels a bit unreal,’ I say. ‘In just a few hours, you’ll be choosing your desk in 10 Downing Street.’

She grabs my arm and pulls me through the crowd. The foyer of the National Theatre is MC Escher made real: paradoxical staircases, connecting halls, mezzanines and balconies that seem impossible to reach. Today, all of them are rammed with aides and party workers, candidates and tomorrow’s ministers. Actually, today’s ministers.

Marilyn turns back to me. ‘Come and work with us, Gil.’

Is she joking? For a moment I feel excited by the idea, and then guilty, a little ashamed, soiled. This is how my sister was seduced.

‘I am not sure that would be good, for either of us.’

Either she can’t hear me properly over the din, or she’s too drunk to notice my frostiness. ‘Johnny is impressed with you, really likes you. He wants you to join the team.’

Really? Johnny actually said that? It feels abusive. I react. ‘That’s flattering, Marilyn. But Johnny would have to be the world’s most extreme narcissist to fuck one Peck and then think it’s a good idea to fuck the other one. But then, he is an utter narcissist, isn’t he?’

Marilyn comes to a sudden halt and I bash into her side. She turns and stares at me. ‘What the fuck are you saying?’

‘You lied to me, Marilyn. You knew Clare was my sister, probably from the beginning. And you knew how often they were meeting, and that theirs was not a normal professional relationship. You knew they were having an affair.’

She looks around, flustered, anxious we’ll be overheard. Everyone is delirious at the victory. No one is paying us attention. ‘You’ve gone mad. Stop it.’

‘Now I understand why Johnny was the only person in the country who thought he could lose the election. If it came out that he was fucking a Treasury official who was breaking the Official Secrets Act, if it became known she was pregnant, that would have been impossible for him to survive. The scandal would have finished him, and Labour. Perhaps forever’. I have a blinding realisation of quite how stupid I’ve been. ‘I trusted you, Marilyn. I told you everything about Clare. Even that she was pregnant. You knew more than anyone else. And you reported it all back to your boss, didn’t you? You manipulated me.’

Marilyn is about to reply when a commanding female voice pre-empts her. ‘Marilyn!’

My jaw clenches. It’s Rona, Todd’s wife, forcing her way determinedly through the mob. She has changed out of the Dior and into jeans, cowboy boots and a tight-fitting T-shirt embroidered in red sequins with the slogan ‘Modern Labour’ on the front, and ‘Modern Britain’ on the back.

‘Found you,’ she says triumphantly to Marilyn. ‘Johnny needs you. Now, darling! He’s having a last-minute wobble about his words to the adoring nation.’