The hemming and hawing of the River Thames

image generated by Craiyon

Crossposted to r/ImaginaryLondon

I have a friend named Geoffrey Jones who delights in confounding expectations and who is annoyingly good at doing so. He told me once that there are parts of the Thames that flow underground. Not those shifting cross-sections of the river that drift on passive, slow-turning currents underneath the dank bridge arches that span the upper and middle course, but significant expanses of the river that are permanently covered over and never see any daylight.

I cannot claim to have rambled along the full 215-mile extent of the Thames. That said, I have explored winding stretches of its banks in piecemeal fashion. I have visited the inauspicious site of the river's beginnings and source of its constant renewal - a waterlogged meadow outside the village of Kemble. I have explored its sketchy early meanderings that unseam the boundary line between the counties of Gloucestershire and Wiltshire. I have lived within walking distance of its middle course where it unwinds with slow grandeur through Oxfordshire and Berkshire. I have followed its looping passage through the layered skyline of the Capital, broadening as it sheds the last of its bridges and commences its final run between Essex and Kent and thereafter into the North Sea. I have lived for almost my entire life on the Thames delta. I can see a small part of the tidal river from the upper floor of my house – an abridged landscape framed as portraiture by a residential vista.

With the possible exception of the Thames's very early stages, I have never seen any part of it that is culverted. Beyond a certain breadth of the channel, I do not think that it would be a very easy thing to accomplish, or even desirable, given the river's status and mythology.

“Well, I am not talking about the river in its entirety but rather the bits along the edges,” said Jones. “The Under Beach or The Under Embankment as it is often called in London. Where the Thames is allowed to creep underneath it formal borders when the mood takes it, as a flood prevention measure.”

The metropolitan sweep of the river is home to a characteristically large-scale and self-celebratory piece of Victorian flood defence called the Thames Bed Sluice. It runs intermittently along an 11-mile stretch of river between Hammersmith Bridge in the west, and Tower Bridge, located just east of the old Roman Walls.

It is best imagined as a sequence of letterbox gates that allow the river passage into hollow subterranean spaces under the embankment wall. Those parts of the metropolitan Thames, which are rigidly channelled between the walls where there are no sluice gates are described as being 'hemmed'. Those areas that are contained within more fluid boundaries, where the sluice is present and operational are said to be 'hawed'.

The London underspill is mostly corralled in a series of canal-like reservoirs that form the broken line of a parallel river. However, the most impressive section of the sluice is the Northbank Trueshore – A one-mile sandy crescent, arcing beneath the north Embankment wall between Embankment Tube and Blackfriars railway station.

In May of this year, a man named Ronald Orders offered to give me a private tour of this underground beach. Orders is a steward for the Unified Wells & Aquifers Company, where I am also employed in an hereditary position.

We rendezvoused at the York Watergate in Victoria Embankment Gardens. The Watergate is a 400-year-old relic of 17th century London topography – a strange combination of crisply chiselled architecture and rain-worn columns that look like they were poked with sticks while the stone was still wet. Though it currently stands 100 metres from the riverbank, it once marked the north shore of the Thames.

“It still does,” said Orders. He searched the large ring of keys that was attached by a braided cord to his belt counting them off, one by one, under his breath. When they were not in use they occupied a leather drop satchel that was strapped to his thigh.

“I'm sorry but I can't undertake my formal duties until I pass through the gate,” he said.

~

There are many semi-secret entrances along the embankment that allow access to the Northbank Trueshore. In Victoria Embankment Gardens, Orders unlocked the nondescript door of a generator room. He led me past a compact labyrinth of redundant pipes and valves that was fenced with diamond wire, then down a spiral staircase fashioned from stone and garnished with Victorian ironwork. A string of grimy, lozenge shaped lights screwed into the walls, and connected to each other by a painted insulated cable, followed us as far as the third-bottommost step.

Then, incredibly, we were standing on a beach of coarse sand and shingle. All around us, near pitch darkness, weakly illuminated here and there by small lights staked out on waist-high poles – their fuzzy glow so feeble and ill-defined that it was like watching stars going out at the end of time.

Orders had dimmed his lantern, possibly for dramatic effect. He raised it up above his head throwing light onto the vaulted tidal cellar, open-sided at the south end, though I could not see it. The river slips in through a gap at the base of the embankment wall, though from the high shore its presence must be inferred from the relentless pull of the tidal wash pawing at the beds of loose stones. Approximately 10 metres overhead, the stone ceiling that passes for the sky, drips sporadically like a sullen and overburdened rain-cloud.

Eerie walking out. A hint of ancient Egypt when you get within sight of the under-river; the dark Nile; dark conjoined twin of the River Thames. The lantern light planed into two dimensions, ribboning against the braid of the current. When Orders extinguished the lantern, it was like staring into the unfathomable blackness of my own private universe.

“Some people wrongly think that the river has aged itself thin,” he said.

I waited for him to say more. The lap of the encroaching waves and the occasional spatter of the roof drops filled the dank silence.

Finally he brightened the lantern. He shone it up and down the foreshore.

“That's not a London Underground carriage, is it?” I said, as I squinted in the direction of a long, vaguely cylindrical object beached along the fringes of the gloom, where it was on the verge of becoming a silhouette.

“I am told that it slipped the siding and derailed into the District Line drainage system, sometime during the 90s,” said Orders. “Nobody on board, thankfully. The only way they could remove it was to open the grate and let it out into the Thames, where it was immediately drawn into the Under Sluice. Those responsible for the accident didn't report it. For years Transport For London was convinced that one of their carriages had gone missing on the line. Some people broke in to the Trueshore a few years ago and turned it into a small movie house. They held a guerrilla screening of The Rocky Horror Picture Show.”

~

Corralled by the pool of light laid down by Order's lantern, I explored the nondescript beach. Tiny white crabs, scavenging at the tideline, hastily burrowed into the wet, grainy sand as I approached. He seemed reluctant to allow me too close to the Underground carriage.

“That's it really, he said. “Another time I'll take you you to the Gamed Hem in the old city. It's a closed sluice. All private beaches along that stretch, separated by wooden groynes. It's a designated fishing spot. The traders at Old Billingsgate Market used to put out heading nets.”

The wet scurry of a small animal ploughed a furrow through the tidal waters.

“A rat probably,” said Orders. “You don't get as many down here as you would think. Richer pickings on the surface.”