If you want to see the eighth wonder of the world, you have to pick up the keys from the ticket office of an Underground station in east London. Not that they'll part with them to just anybody. After all, they admit the bearer to the Thames Tunnel, which was the first to be built under a river anywhere in the world when it was driven through by Isambard Kingdom Brunel and his father, Mark.
As a trustee of Brunel's engine house nearby, Robert Hulse doesn't have a problem persuading the Tube people to hand over the wondrous keyfob. Robert is also an impersonator of the great engineer, or "IKB", as he calls him. You feel it's a pity that Robert doesn't turn up at the Underground wearing his other hat. It's a stovepipe.
Leading the way inside the tunnel's disused shaft, which is capped by a rust-coloured outhouse like a sawn-off gasometer, Robert outlines plans for a modern excavation worthy of the historic surroundings. What he and his colleagues are contemplating is digging the tunnel out all over again, not from London blue clay this time but from the neglect into which it has sunk.
Don't get me wrong, the trustees run a spotless engine house, which is open on weekend afternoons and full of curios including a china gin flask, which was cast to commemorate Brunel's feat. Nor is the tunnel itself idle. The East London Line runs through its elegant arches, as I was able to confirm in the shaft, by craning through a kind of dumb-waiter to watch the trains some 40 feet below. (From a seat in one of the carriages, you could dream that you commuted in marble halls.)
But the tunnel is not the attraction it was. In the 19th century, a million people came to see it in the space of a fortnight, and fashionable society joined Brunel for a famous subterranean banquet. It was the Germans who considered that the tunnel narrowly lost on points to the Hanging Gardens of Babylon in the world wonders' rankings. But the Times dubbed it "The Great Bore" after it took one too many soakings, financial and riverine. It was the Millennium Dome of its day. Now the idea is to turn the shaft into a kind of perpendicular museum. It is, after all, steeped in history, the place where Brunel Jr was saved from drowning when he was plucked from a spout of water after the tunnel was inundated.
As for Robert's other life as an IKB lookalike, he says he's got a "pensioners' gig" coming up. He's an actor and pal of Pulp's Jarvis Cocker. If you think you know him from somewhere, it might be the lager advert in which he played a rush-hour motorist taking the direct route to the bar, scaling the gridlocked bonnets of other vehicles to the tune of Gary Numan's "Cars". In retrospect, this looks like a canny way of reaching a mass audience with the trustees' message about cherishing public transport.