My final walk will be here or somewhere nearby. When I dive into its cold bed, neither it nor I will weep for any lost time. Small waves will swill over me casually and stones in my pockets will pull me through its depths. I can do it. I’ve never doubted that for a second. If I have to. I can’t stay another day in a cell.

I’m no longer as calmed by the thought of leaving nothing behind as I once was. To arrive with nothing and to leave nothing behind has a poetry to it, but now that I’m here at the threshold of an exit, I’m no longer sure about poetry.

It’s not until I step on to south London earth that I feel the security of home. For nearly thirty years I travelled without borders and I managed to get only as far as here. We came here, Grace and I, just to feel separated from London and now I wonder whether you can be separated from London. Because the city is not under your feet but on your skin.

It’s still before midday and I don’t need to be back at Seb’s for any reason that I can think of. I wander past the road that leads there and press on up Lordship Lane. Within a few minutes I am back at the Horniman grounds. Grace pulls me here again, but today I pull along in the same direction.

I need to find it.

When I walk through the gate, I do it as a person. For once I am not in hiding or exile. I can walk in with the other people and blend in with them. At first, I am self-conscious about my beard but then I realise that there are more bearded than clean-shaven faces around me. Fashion seems to be in a curious phase – suits without ties, and beards everywhere.

In this new disguise, in Seb’s suit, I discover a thing. People smile at me. I want to smile back but the joy is trapped somewhere underneath, like an air bubble.

I pick my way around the perimeter of the grounds, skirt the edge of a sunken ornamental pool and walk uphill. When I reach the top, there is a view of London that stretches out for miles: the Shard, the Gherkin, the Walkie Talkie. London has changed so that there are now pinnacles of glass at every turn. All these buildings with names fit for children have sprung up as if from a giant pop-up book. Grace might have loved this change. Or hated it. Or accepted it, grudgingly. Instead she missed it.

There are a few people by a bandstand, taking in the view, as I crest the slope and walk round the edge. And then I see what I am looking for.