The River Tyburn was a small northern tributary of the Thames, it would be more accurately described as a stream than a river. Located between the Westbourne River in the west, big surprise, and the River Fleet in the east, its course ran from South Hampstead down through St.John's wood into Regents park, on through Marylebone and Mayfair, crossing Piccadilly and into Green Park. After crossing centrally through Green Park and passing Buckingham Palace its lower course is subject to some speculation and there are various theories in this regard, we're not about to delve into them here. Our interest is firmly focussed on the varied underground channels that convey any remnant of the Tyburn's flow; known collectively as the King's Scholars' Pond Sewer (KSPS) there is no speculation over its route to the Thames.

Over the course of various visits we have, in part, re-traced the footsteps of the intrepid Victorian writer John Hollingshead, who ventured through the same sewer in 1862. Hollingshead tackled the entire five mile downstream journey from St. John's Wood to Westminster in a single trip; this is made a little more difficult today due to the connections with Bazalgette's intercepting sewers, connections which must have been imminently due for construction at the time of Hollingshead's trip. Our journeys have seen us cover the lower two and a half miles of the KSPS from the approx vicinity of Oxford Street, at its junction with the Mid Level #1 Intercepting Sewer, down to its Thames outfall in Westminster. Rather than re-tell the tale of a single trip it seems more worthwhile to attempt a run-through of the distance we've covered.

Starting at our most northerly point reached to date, heading downstream towards the Thames, we encountered the first of several significant changes made since Hollingshead's journey. The connection that now diverts the sewer flow into the Mid Level #1 Intercepting Sewer has drastically altered the tunnel architecture, so much so that Hollingshead might well not recognise this juncture were he able to stand in it today. The older, flat-sided, arch topped sewer tunnel would originally have simply taken a ninety degree turn here. When it was connected with the intercepting sewer at this point it seems there was the need to factor in some sort of a buffer for the downstream stretch of tunnel. The solution was to drop the entire corner section, which was to incorporate the diverting pipe, down some ten feet from its original depth. The lowered section has a stairway into it at its upstream end and another, marginally lower, stairway out of it at its downstream end. It's a very elegant solution, effectively creating an inline storage facility to allow the interceptor to deal with excessive flow, if the storage reaches capacity it overflows into the main tunnel and on downstream to be diverted again. Of course the greater volume of sewer flow that can be directed into the interceptors at these higher points in the system the better. Features such as this inline storage allowed the interceptor to deal with more flow, reducing the volumes heading downstream, thus reducing the risk of overflow into the Thames and helping to transform a once squalid river. Further evidence of the tunnels original depth and subsequent lowering is seen in a branch sewer which joins on the same bend; it too joins by a drop of stairs, atop which is the original level it would have joined the main tunnel pre intereceptor connection.

At the point where the upstream section of the original sewer enters the lowered storage section the flow cascading down the stairway is pretty well unpassable for those not willing to take a grey water shower, see above pics. So, heading downstream the sewer was a comfortable standing height at around seven foot, there was initially little flow due to the interceptor connection, although there were some particularly gargantuan Richard IIIs decorating the tunnel floor that must have had to be epidurally assisted. The brickwork throughout was of the highest calibre and the combination of angles, grades of brick and damp surfaces was enough of a spectacle in the right light that you momentarily forgot you were tip toeing through Londoner's waste. Hollingshead's downstream journey did not begin quite so comfortably as ours. Starting in St. John's Wood saw him adopting the all too familiar back-breaking stooping posture for approx a mile and a half prior to reaching tunnels of standing height. A stooped gait and deep, fast flowing sewage inevitably results in nasty splash-back incidents, I can imagine him frantically wiping poop soup from his mustachioed face with one hand whilst keeping a tight grasp on his flickering lantern with the other.

For the first mile and a half of our downstream journey the tunnel varied in form occasionally and was host to many adjoining side pipes and chambers of varying construction. Along that first mile and a half is the impressive overflow chamber, where The Egg storm relief sewer begins, its the only point along that stretch where the main tunnel dimensions exceeded an approx seven foot high by six foot wide. This chamber is another feature that Hollinsghead would not have been witness to; for him the tunnel here would have just continued along at the same dimensions and featured a couple of adjoining branch sewers, one of which is now conveyed into the main pipe via a bolted cast iron pipe than spans the overflow fall. Of the many adjoining side pipes we passed heading downstream one particular short passageway lead to a circular, brick built, dome topped chamber, capped with a circular manhole cover. The chamber was fifteen foot high from the manhole cover at its top to the water pool of unknown depth that resided at its bottom. With no access steps or ladders or any indication that there had ever been any we were somewhat bemused to its function. On one side of the manhole cover a tree root had long ago begun a hunt for moisture, now suspended in space the root had spanned the fifteen foot fall. Inter-twinned around itself, as thick as a mans forearm at its top, its many tapered and split ends were like the tongues of reptiles all drinking deeply from the Tyburn. London may have forgotten about this watercourse but nature certainly has not.

So on to the lower course of the KSPS. The debate over the Tyburn's lower course from Buckingham Palace centres around whether it headed east towards Westminster, south-east towards Vauxhall Bridge, or both. The KSPS heads south-east, forming the western boundary of the City of Westminster and fuels two of the three Tyburn theories. This lower stretch was referenced as a sewer, named 'Kingschoole Sluice', in local government documentation as far back as 1672. Previous to being a sewer there's no doubt that the route existed as a drainage channel through the surrounding marsh land of Tothill Fields, whether it was an arm of the River Tyburn is of course too big a question for a website dedicated to drains and sewers.

Existing as an open common sewer until 1800 this lower stretch was covered over in a somewhat piecemeal manner in the years to follow. By 1862 when John Hollingshead found himself approaching the sewers end reaches the only open section of the KSPS was the very end 300 yards from Lupus Street down to the Thames. Judging by Hollingshead's account it's safe to assume that the KSPS wasn't benefitting from connections with the newly constructed intercepting sewers. The last leg of his journey was made by boat! Floating out of the arch of the sewer and into the open channel he writes 'our bark had floated out of the broad archway of the sewer . . and we were anchored on that pea-soup-looking open creek'. The open channel was brick formed, twenty foot wide by fifteen foot deep, a sluice house was located over it towards its end, where tidal gates closed the Thames outfall. The site of the sluice house was later occupied by a pumping station and the Lupus street arch was furnished with four huge hinged wooden flaps to close off the sewer. Amazingly this one remaining stretch of open sewer maintained its status as such for another one hundred years plus post Hollingshead's visit. This last stretch of drainage ditch that had existed aboveground as part of the Westminster landscape for many hundreds of years finally met its end in the late 1960s; a concrete pipe was run along its length to convey any overflow to the Thames and it was unceremoniously filled and forgotten. I shouldn't complain, it's another facet to the story of the KSPS, of course I'd much prefered them to have simply covered the channel, it would have made for so much more fascinating viewing. As it is it serves as an abrupt visual reminder of the development of engineering technologies over the course of one hundred and fifty years.

Our travels through the KSPS are far from complete, if we're to pay Hollingshead the homage he's due then we've got the same distance over again to travel upstream. :)

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