“I went out along the jetty to the pond. It is deep, up to twenty feet, and the water is green, smooth and cold. It is entirely natural, and samples are regularly tested for purity. It was icy cold, and I swam fast in a big circle round the buoys the lifeguards use to moor rowing boat, past an unconcerned coot or two, and back to the ladder, feeling what they call here ‘braced’”.

Highgate Men’s pond, which sits nestled in an eastern corner of Hampstead Heath, is a century-old institution. Protected from development since being added to a parliamentary act covering the entire Heath in 1889, swimming here is a daily ritual for some and an indulgent midweek activity for others (read me and my fellow wild swimming acolyte Joe).

Arriving on a warm, late summer/early autumn afternoon, only one swimmer drags himself around the roped perimeter of the swimming area as we walk across the Heath, locking up Joe’s bike before paying our voluntary £2 fee. The latter has been the centre of some dispute this year, with the City of London attempting to make the charge compulsory, much to the chagrin of regular users and locals (as this excellent piece from The Kentishtowner details). Roger would doubtless be appalled.

When he arrived here as part of his outdoor swimming tour of London, for one of Waterlog’s final chapters, it was November, the leaves falling and the water temperature dropping. He would have most likely strolled in for free. But, weather aside, today he would find it much the same. The ‘Nude Sunbathing’ sign, the spring diving board at the end of the concrete jetty, the buoys marking out a huge swimming area.

Eschewing the spring board (I’m more Gareth Bale then Tom Daley when it comes to diving, sadly), I lower myself down the runged ladder and into the chilly water. It’s 19C according to the blackboard in the changing rooms, but as I dip my head under the green water, the sun goes in and a distinct chill comes over the water. I strike out for a far buoy, a Great Crested Grebe bobbing along in the distance. I find myself following Roger’s formula, swimming as fast as possible between buoys, completing a couple of huge laps before demisting my goggles while lying prostrate over a floating safety ring.

The water here is delightful. Fed by the now covered River Fleet, Highgate Ponds has a silky, heavy quality unlike the River Granta, where I swam a couple of weeks ago. You have to work hard to push through it, but it rewards long strokes with much-needed bodily warmth. Sadly, the latter isn’t in evidence after we haul ourselves out of the pool. We shiver as a local flies off the end of the board, his legs splashing down as we look on and offer a small round of applause.

The Men’s Pond might not offer quite the same seclusion as the Mixed Pond across the Heath. But there’s a greater sense of community, of people coming here to escape London and its noise and grime, even if just for half an hour. It’s a magical spot.