Beneath the streets of Holborn, something is growing in the Kingsway tram tunnel.
The usually padlocked doors at the tunnel's Southampton Row entrance, which last saw tram traffic when a young Queen Elizabeth II had been on the throne for just a few months, have been thrown open to welcome visitors for Chord, a month-long art installation by Conrad Shawcross.
Led in by a flourescent bib-wearing guide, we descended the surprisingly steep ramp and into the tunnel itself, passing fake posters and non-existent Tube station roundels left from a recent film project. As we penetrated the murky gloom en route to Aldwych, passing by the remnants of the Kingsway station platform, a curious contraption finally hoved into view.
As a fairly unusual site-specific installation Chord is the kind of folly that a writer could trip over in trying to describe, whereas it's much easier to comprehend in situ, so we'll avoid trying to capture what's going on in prose and refer you instead to the pictures. But really, the best thing to do is not look at the images at all and just get down there yourself to see it. A series of Heath Robinson-inspired pulleys and ropes stretched along a section of track, Chord is, according to exhibition blurb, "concerned with the human perception of time, as both a linear and cyclical notion", and the constant motion of the piece means it expands through space at a rate of five metres per day. We're intrigued to see how large it will grow by the show's end.
Art aside, this is of course a rare chance to visit the Kingsway tram tunnel, and despite the brevity of the half-hour guided tours this is an opportunity that transport buffs, professional nostalgists, amateur spelunkers and the plain curious will not want to miss.