Southeast London's two lost rivers, the Earl's Sluice and the Peck, merged somewhere in the vicinity of South Bermondsey station. It's no coincidence that this station lies on the border between Southwark and Lewisham. If you trace the borough boundary from the Old Kent Road up Ilderton Road you're following the route of the Peck, near enough. And if you carry on along that same boundary to the east, you're following the final mile of both rivers down to the Thames, pretty much. Indeed, these rivers once marked the county boundary between Surrey and Kent, which is impressively significant for a minor river that no longer exists.
For the best view of the area, head up to the elevated platforms at South Bermondsey. The footpath from the street is ridiculously long (all the better for corralling football supporters), and the curving narrow platform almost longer still. From the tip you can even peer down through a gap in the stands at The Den and watch Millwall play, so long as the ball's in one specific tiny patch of pitch. [photo]
My river walk continued down the embankment, outside the stadium, on one of the gloomiest streets I've ever encountered in central London. That's Bolina Road, a bendy backwater which burrows its way beneath as many as five railway viaducts in quick succession. The first cuts you off from the outside world. The second, and loftiest, is blessed by a pile of boulders and abandoned tyres at its base [photo]. The gap between here and the third feels scarily oppressive, as if some ne'erdowell might leap out at any moment and your body might not be found for months. The fourth is low enough to slice off the entire top deck of a bus, although its precise height is unclear because the official road sign's long since vanished. And the fifth is so narrow that cars wishing to pass have to honk their horns lest they meet a car, bike or even pedestrian coming the other way. I moved on fast.
It's hard to imagine the Hawkestone Estate as riverside fields (and worrying to imagine which council committee thought 'Regeneration Road' was a good name for one of its new streets). Another railway bars progress before long, this time the East London line, with a welcome footbridge at the point where the spur to Clapham Junction will one day divert. A thick white pipe crosses the tracks close by, reputedly the sewer-borne remains of our lost river, flirting anonymously with the open air. There's one last inferred sighting at the top of Rotherhithe New Road, where a green stinkpipe rises from the triangular traffic island. 200 years ago the view round here was rather more peaceful, with the Earl's Sluice rolling by beneath an arched bridge.
One last push to the Thames, along a stretch which last saw the light of day as the "Black Ditch". On Chilton Grove there's conclusive evidence of the river's burial - the Earl Pumping Station. It's housed in a boxy brick structure which could easily be a 1930s library, but instead houses some non-cutting-edge Thames Water pipework. You might expect the river to have flowed along the line of the South Dock [photo], but cartographical evidence suggests its replacement sewer follows Plough Way. A memorial stone inlaid in the pavement wall, past Baltic Quay, confirms that the former Kent/Surrey boundary passed this way (until 1899). It makes sense - those are indeed the Surrey Docks just to the north on the non-Kent side of the divide. [photo]
The final few yards in Helsinki Square are marked by what looks like a filled-in dock, lined by 21st century trees, leading to St George's Stairs [photo]. At low tide a pebbly beach is revealed alongside a pair of rotting wooden piers [photo]. Don't be tempted down the steps - a bold yellow Thames Water sign warns of a "sewer outlet 30 metres out from this board". Stay on the riverside promenade, turn left, and you'll find a preserved brick wall from a bridge over Earl's Creek. It was shifted here in 1988, and includes yet another boundary stone to admire. Surrey/Kent, Rotherhithe/Deptford, Southwark/Lewisham... not a bad tally for the former Earl's Sluice/Peck.