An email from someone called Piers White  tells me that the start is “in the west of the park (Boules area)”. But it is a black night and the park is plagued by licks of mist and off the lit pathways it is dark enough to think about muggers. I jog around heading west and looking for the start. I find it: an inflated archway branded Red Bull and a large white registration tent, music. Hundreds of people! I have the impression – creepingly familiar – that everyone is younger than me, and better looking, and fitter. Expensive looking training kit advertises university teams and city firms. British Ladies. Munster Rugby. OURC. Accenture.

Inside the tent it is warmer and here I stretch and watch and wait. Outside groups of friends and team mates stand together in the cold, laughing and joking and teasing one another. I know no one here. I like the anonymity – I think that I’d like to hold onto it.

At 7.30pm the race starts. We set off through the park, running out parallel to the river on a 2.5km loop. We are running for an extraordinary and inspiring fellow called Mark Pollock. All the runners wear a band on one arm which flashes red. In the yellow light of intermittment street lights the ground is a non-colour closest to plain chocolate, underfoot the crushed leaves of the plain trees are the colour of banana skins and wet sand. The field thins as the faster runners pull ahead and the slower runners fall behind. I run into eddies of sound and then into silence. Pieces of other people’s conversation: “she’s gone mental!” / “he’s got reflux” / “very Credit Suisse” / “like fucking reindeer” / “easier” / “harder” / “faster” / “rest now”. Gradually even the most talkative are worn down and fall quiet, so all the noise we share is the soft tread of our running shoes, the heavy breathing of someone in pursuit.

We carry on. I spit a good deal. There are plenty of pretty girls and their silent, methodical presence lifts my spirits and makes me try harder. At opposite ends of each loop in pools of white light groups of shouting men play hockey and football on artificial pitches; steam rises off the mens’ shoulders. As we pass by we pay them little attention. Between the pools of light we run through the dark; we run in alliances and in squads of identikit t-shirts and in dalliances and I run alone. I run along on my own and I love, literally love, the anonymity of this crowd of good-looking kind-hearted strangers who I run alongside and who I am prepared to abandon without a care. The  flash and sparks of commuter trains heading out of Victoria flare against the grey side of a gas holder.

This is London. This is possibly the best ever time to be alive.

My last lap is my fastest. Isn’t that exactly what is meant to happen? I finish the 10k in 49 minutes and 53 seconds. Through the Red Bull arch I lean against the trunk of a plain tree catching my breath. Each of the runners are handed a doggy bag as they cross the finishing line. Mine contains a bottle of water, 1 x limited edition caramel Mars Bar and 2 x packets of Dooyoo Velvet Crunch Cheddar Cheese and Spring Onion Flavour crisps. I drink some water, eat a bag of crisps and walk away into the night.