In Merton, by the River Wandle, there's an arterial road through a retail park. Underneath the arterial road there's a subway. And in the subway is a door that's usually locked, but is occasionally opened to reveal a medieval secret beneath the carriageway. That'll be Merton Abbey Chapter House(1114-1538). And it was open to visitors yesterday, and it's open again today.
The immediate locality has a peerless history. The Romans built Stane Street directly through the site, and then a millennium later Gilbert, sheriff of Surrey, established a priory church. It grew to become terribly important, esteemed by royalty, and a stop-off for King John on his way to sign Magna Carta. Famous pupils at the priory include Thomas a Becket, and also England's only Pope, the almost famous Adrian IV. 500 years ago Henry VIII razed it to the ground, and the riverside site was reappropriated for water-powered industry - William Morris would eventually choose to site his textile mills here. A lightly used railway passed through, including an even less frequented station called Merton Abbey, closed in 1929. The majority of the priory's ruins are now lost beneath a giant Sainsbury's hyperstore, thankfully dug over by archaeologists before the car park and frozen meat aisles went in. Then in the 1990s the council built a new trunk road, Merantun Way, along the line of the railway, except this was precisely where the Chapter House's foundations still lay. So they raised the carriageway slightly, created a concrete-topped chamber underneath, and Dorking-bound traffic now drives obliviously across the top.
The site today is horribly blandly out-of-townly commercial. The Sainsbury's is a giant box above a car park, now coupled up with an M&S to lure the car-driving populace of SW19. Across the road is an architecturally dead Premier Inn, plus a Pizza Hut and a KFC of the kind that uninspired families drive to after work. Admittedly Merton Abbey Mills down by the river is rather lovelier, with William Morris's works now populated by craft stores and restaurants with a splash of character, and a waterwheel that still turns same as it ever did. But there's no joy to crossing Merantun Way through the subway, descending past the foot of an electricity pylon, not unless the door in the wall is open.
It was open yesterday, if only the passing shoppers could be bothered to step inside. Initially they were more fixed on grabbing a trolley than on archaeology, and once they had bulging orange bags it was too late. But several folk had come deliberately, having seen the rare opening was taking place, and I overheard at least one couple say "Oh, I've always wanted to look in here." Spread out beneath the low grey roof is a dimly-litchamber, perhaps the size of two tennis courts, with a staked out border around a sandy expanse in the centre. This is approximately the shape of the old chapter house, the remains of whose stone walls can be seen raised intermittently along much of the perimeter. One end curves more than the other - this used be the apse - hence the bulge you'll have seen in the subway wall outside. If you're good you'll be allowed to walk out into the centre of the room for a closer look, and if you're a small boy called Rufus your parents may allow you to play in the 'Archaeology For Young Children' sandpit dig, at least until it's time to insist that you stop having fun and leave.
It was in this very room that The Statute of Merton was drawn up in 1236, an agreement between the barons and the king along the lines of Magna Carta, and generally considered to be the very first English parliamentary statute. Various aspects of the site's history are explored around the edge of the room, including that of the priory itself and the dig that rediscovered it. Bits of masonry may, or may not, be from the original abbey, and several of the sheets stuck up on the displays have a slightly faded "we found this in a magazine" feel. A particular focus is the work of William Morris, including catalogues of wallpaper, a few Liberty dresses, and a small Arts and Crafts bedecked sitting room, which manages to create the right atmosphere out of not a great deal. If you're smitten there's a table of heritage related goodies in the far corner, most of them paper-based, and probably a gaggle of volunteers to whom all credit for the attraction's opening should be directed.
There are plans afoot to open up the Chapter House to a wider audience. Almost £200,000 has been set aside by the Lottery and the council to create a proper Visitor Centre, the main effect of which will be to replace the southern wall of the enclosure with a new glazed wall so that anyone can peer in, and to greatly improve illumination. Part of the plans will also provide a toilet, a kitchen and a dedicated storage space, elevating the basic facilities to the level of say a small church hall. Eventually there'll be an education centre, even a cafe, and a thin extension poking out beneath the elevated roadway running parallel to the medieval walls rather than constrained by the road. This may take a while, but in the meantime the Chapter House is open on a handful of weekends a year, including September for Open House, and this weekend as part of the Festival of British Archaeology.
As Ian says, the site is quite small so it's probably only worthy of a diversion if you're in the local area, or if you like this kind of thing, which obviously we do. In particular it'd be nice to think you could tear yourself away from your shop at Sainsbury's and take a peek under the road you just drove in along, to view an amazing survivor of some importance, because who'd ever have thought?