‘We’ve only got a few minutes,’ Marilyn warns me. ‘He’ll be out soon.’ She peers at me closely. ‘So what’s so bloody important that you have to make a detour to Bermondsey to tell me? And before you ask, no, I’m not going to marry you.’

I smile briefly. ‘Look, you probably think I’m mad but I have good reason to believe Clare was having an affair with Kendall. That it was his baby.’

Marilyn blows out a long stream of smoke. ‘Fuck.’

‘Yeah.’ What else is there to say? For a moment, the two of us stand without speaking, to a soundtrack of London traffic, construction and birdsong that won’t be drowned out.

‘I can’t decide whether this is massive and important, or whether you’re just nuts,’ she says. I can tell her mind is already calculating what it means for the election.

‘For fuck’s sake, Marilyn, I didn’t tell you this so you could use it.’

‘I get that. But I can’t exactly un-know it.’ Her face flushes. ‘I wish you hadn’t told me. Just to remind you, I’m advisor to the Leader of the Opposition, and the Tories have moved up two points in the polls in the last week. What do you expect me to think?’

‘Well, you could show a bit of empathy? How do you think I feel?’

She reaches out and squeezes my hand, with a glance over her shoulder in case the Special Branch men are watching. She’ll never be too careful. ‘Imagine what would happen if it became public. Something like this would completely knock the props out from under the corrupt Tories. They’d go down to the biggest defeat in a hundred years. From what I know about your sister, she’d want that. Wouldn’t she?’

‘Maybe.’ I don’t know. Would she want the misery and humiliation that my parents would suffer? Would she want the playground teasing that would be inflicted on her boys? A wave of anger surges inside me. I kick one of the Coke cans. It flies through the air and lands with a rattle that draws surprised looks from the teenagers and the Special Branch. ‘Just to be clear, this is my well-sourced surmise. But there’s not enough undeniable evidence. Or at least not yet.’

‘Do you want me to do some digging? See what I can find?’

‘I don’t think you’re hearing me, Marilyn. I am talking to you because I need to talk to someone.’ I stick my hands in my pockets, trying to make sense of my chaotic thoughts. ‘But it must never get out. It would destroy my parents, Clare’s family, me! Think about her reputation.’