Instead of crossing Parker’s Piece, he turns right down Mill Road, an area he never visited as a chorister. Martin calls it the guts of Cambridge, which William thinks might suit him better right now than the historic centre. A tattered tweed coat and a pair of shoes with flapping soles catch his eye. The vagrant is walking down a gravel path he’s never noticed before. At a distance, he follows him into a graveyard full of wonky headstones covered in lichen, leaning into the earth at extreme angles. Tired, he sits on a bench against a wall.

‘William?’

Colin looks different. Like himself, but turned up a few notches; cheekbones sharper, hair wilder. He slumps down on the bench.

‘I’ve been looking for you for days. Where’ve you been?’

‘London.’

‘How long for?’

‘As long as it took me to beg my train fare back.’

‘Here.’ William hands him the bag.

Colin looks at him, holding the bag tentatively. ‘For me?’

William nods.

He opens it and puts a sandwich straight in his mouth. He reeks of booze. William has never been conscious of it on Colin. Some of the men drink heavily before choir, but William wonders now if Colin deliberately arrives sober.

‘Did you see your children?’ William asks, after letting him eat for a few moments.

‘My daughter. From a distance. Opposite the school gates.’ Colin is talking to the gravel path. ‘She looked happy. Laughing with her friends.’

‘You didn’t speak to her?’

He shakes his head. ‘It was enough to watch her for a few minutes.’ He stretches out a leg so he can reach into his trouser pocket. He unfolds a small piece of worn paper and hands it to William. It’s a family photograph; recognisably Colin, with his wife and two children who look about five and seven. He points at the girl. ‘That’s Katy. She’s taller now and her hair’s shorter.’

‘Is that their address?’ William points to the reverse side of the photo.

Colin nods.

‘You said you didn’t know where they lived.’

‘I could never show my face, so I may as well not know.’ Colin’s head drops. William’s afraid he’s going to cry. ‘When she took them to London, my wife said if I got myself straight, I could see them.’

‘Martin told me you couldn’t.’

‘I can’t if I’m on the booze. And I can’t come off it, so it’s the same thing. And anyway, I don’t want them to see me like this.’

‘Tea?’ William holds up the flask.

Colin nods but looks in the bag. ‘Club biscuits. Haven’t seen these since they were in my kids’ lunchboxes.’ His body straightens all of a sudden. ‘What’s the time?’

William checks his watch. ‘Ten past five.’