THE UNLOST RIVERS OF LONDON Bonesgate Stream Malden Rushett → Chessington → Tolworth (4 miles)
[Bonesgate Stream → Hogsmill → Thames]
The southwestern tip of London pokes deep into Surrey, the boundary sticking out like a tongue. The Bonesgate Stream is the river which drains this elongated extrusion, from a field in sight of Chessington World of Adventures to a rewilded channel on the Watersedge Estate. Most of it flows across private land so in the upper reaches you only get a glimpse, but the last mile is fully followable with a slew of pylons to boot. The somewhat macabre name comes from the river's association with the burial of plague victims, although don't let that put you off.
The Bonesgate Stream has three sources, one marginally in Surrey, but one flows muchfurther than the others so I'll be following that. Everything kicks off amid a gloriously broad field belonging to Rushett Farm, just below the treeline of Ashtead Common. Freshly-planted wheat spreads down to a thin line of trees following the lowest contour, within which the slightest of trickles begins its journey towards the Thames. The first sighting comes from a slab bridge on a farm track where the earth has fallen away beneath a hawthorn in full flower. Keep walking and in a few minutes you could be sipping a flat white in The Barn, part of the farm's diversification into glamping, boutique wellness and corporate awaydays, whose refreshment offering is open to all. But the river, thankfully, isn't going that way.
Instead follow the line of a fledgling hedge, recently planted by CPRE's Hedgerow Heroes, to a second gap in the trees and cross the foliage-shrouded stream. The field on the far side is parched and fallow but also flat, which is why it also doubles up as an occasional airstrip. This looks quite prominent on a map but the uncultivated grass landing strip is really only visible from the air, while from the footpath the only clue is a windsock flapping away in the distance by the farm. The Bonesgate Stream is alas already making a break for privacy, emerging from its oaken sleeve only to dip into a pipe beneath busy Rushett Lane. You really don't want to come to these upper reaches solely for the river but this is excellent walking country, not just for the vast expanse of Ashtead and Epsom Commons but also (as previously recommended) for the Chessington Countryside Walk.
Beyond the road a half-mile-long bridleway sets forth between further fields, bursting with buttercups, brambles and butterflies. Near the halfway point is a bend with a small wooden footbridge where a minor tributary passes, its invisible source somewhere near the Malden Rushett crossroads and/or the Chessington Garden Centre. It feels serene, but a planning notice attached to a post alerts passers-by that a battery storage facility is destined to fill an adjacent field, approved on appeal by a government inspector. Also if you can hear screaming in the distance it's not carnage, it's because Chessington World of Adventures is imminent and the Vampire ride is in the nearest corner. I have never screamed on the Vampire, only grinned wildly, but I digress.
Up ahead the Bonesgate Stream is doing its own thing unseen amid a sweep of fields. Attempting to follow it semi-closely instead requires a road walk past the theme park's very own Premier Inn and Beefeater, then a dodgy crossing of the Leatherhead Road to follow Chalky Lane. Followers of the Southern Combination Football League will know Chalky Lane as the home ground of Chessington & Hook FC, mid-table stalwarts of Division 1, there being no other reason to visit. The surrounding fields would likely have become housing instead had Hitler not invaded Poland three months after Chessington South station opened. Half a mile of additional track had already been laid, terminating here, but the postwar Green Belt kyboshed that and so the unlost river trickles on.
Green Lane is well named, with the occasional view across paddocks to a line of trees shielding the Bonesgate Stream. It should also be very quiet unless you too happen to bump into several teams of schoolgirls on an orienteering challenge belting out "Umberella-ella-ella" at the tops of their voices, because no teacher wants to do proper work on the day before half term. The rural illusion ends as the lane emerges beside a car repair works brimming with smashed chassis, then proceeds past a string of badlands bungalows and fortified detached houses before entering the backside of Chessington. To reacquaint yourself with the river you can follow a narrow alley down to a concrete footbridge over a low dribble, now a couple of metres wide, but only do that if you're continuing up the other side to Horton Country Park because it's no grand sight.
Far better to continue past Chessington's 13th century parish church and the chip shop at Copt Gilders, ticking all sightseeing boxes, then descend into what's now a very pronounced valley. The delightful riverside attraction here is Castle Hill Local Nature Reserve and Scheduled Ancient Monument. Nobody's quite sure when the central earthworks emerged or why, only that a Roman coin was once found here, but the information board says the most likely theory is that it was built for a medieval hunting lodge in a deer park. Feel free to scramble up top or explore the hazel coppices, but the real gamechanger riverwise is the existence of a path alongside the shady Bonesgate Stream, which thankfully continues all the way to river's end.
Welcome To The Bonesgate Nature Reserve says the wooden sign on the other side of the road, immediately underneath a massive pylon plonked down beside the stream. A similar sentinel guards the northern gate, and between them a fizzy catenary hangs high above a stripe of lawn and linear undergrowth. A couple of locations exist where you can duck into the trees and stand beside the stream, such as it as at present after barely any rain, but mainly this appears to be a very popular place to walk a dog. At the next road crossing is a sturdy faux-Tudor pub which used to be called the Bonesgate but is now inexplicably the William Bourne, recently optimised for Sky Sports with the addition of an eighth HD TV screen. Check the culvert and you may spot a narrow metal 'mammal ledge', designed to shepherd small creatures under the main road in relative safety.
This is also the point where the Bonesgate Stream becomes the de facto boundary between London and Surrey for the best part of a mile, generally with footpaths on either side so you can pick your authority of choice. Initially Kingston is more open and Epsom & Ewell more wooded, with postwar cul-de-sacs nudging in as far as the floodplain allows. The Surrey side in particular treats the riverside as a recreational stripe so expect to pass a children's playground, a basketball court and a strangely isolated skateboard ramp tucked away to service the neighbouring community. Try not to focus too much on the residential bin stores, the abandoned mattresses and the feral ratboy revving his moped round a Watersedge car park.
The Environment Agency remodelled the river hereabouts in 2008, removing six austere weirs and replacing a harsh concrete channel with soft-edge meanders. Look down from the cycle path and you'll now see low gravel riffles and occasional log deflectors, all supposedly improving flow diversity and bed scour although it's hard to tell at current river levels. Any fish hereabouts would be far better sticking to the deeper, broader Hogsmill, into whose waters the Bonesgate Stream merges beyond a final white footbridge.
Cross here to follow Tolworth Court Farm Fields back to civilisation or maybe piggyback onto London Loop section 8 and meander riverside to Kingston. Not that you ever will but the Bonesgate valley has much to recommend it, be that open fields, ancient earthworks or a 35 year-old suspended swinging rollercoaster.
