I plough on through the crowds on to the escalator, and then see the flash of his red soles on the Central Line platform heading west. It is crammed full. This platform lined with people under its curved walls makes me dizzy.

Please stand behind the yellow line.

A gust of hot, oily air passes so close that I wonder that they are not drawn into the track by the pressure differential. The Bernoulli principle. I shake that thought off. I still have my eye on Ebadi who is on his phone, sandwiched between commuters. A train screeches along the platform and stops. We all bundle on, squeezing into every available space. In the crush I lose sight of him for a moment until I see him through the glass in the doors dividing the carriages. He seems carefree. He checks his expensive watch and then lets his arm dangle by his side.

It’s when we approach North Acton that I see Ebadi patting himself down unconsciously, waiting for the doors to open. I hang back until the last possible moment and then I jump off too. I pick up a Metro newspaper from a bench and hold it close to my face as I follow him. I don’t want him to get a good enough look at me to risk him causing me a problem. If l look down at my newspaper, he won’t see me. He presses an expensive wallet against the pad and walks through the barriers.

The daylight is disconcerting. I need to push through the gates behind somebody else but I am exposed by all the light. As I approach them my heart begins to kick up a beat. I can’t easily shadow someone through here. There is a member of staff by the front exit. Ebadi will see immediately if there is a commotion. I shuffle forward slowly, eyes searching out the best option. Then, with relief, I remember the Oyster card Seb gave me is in my pocket.

Outside the sun has vanished from the sky, leaving it steel grey. A few seconds later, as if to confirm the change, it begins to spit out a fine drizzle. Up ahead I see Ebadi, red soles lighting each step. His head is down against the wind. I follow until he reaches a fork in the road – Park Royal Road. Along the left side are some pitiful-looking houses, broken and unloved. To the right there is what seems to be a large park edged by a low brick wall topped with iron railings. He crosses over towards the park and stops at the entrance.

What is he doing here? In a park, miles away from his home? I approach the curve in the pavement, announcing the brick pillars of the park gates. There is a sign affixed to the left pillar which reads MAIN ENTRANCE. And then I see in green letters two words immediately above them and my heart stops.