What I learnt about Britain's past and future from climbing into Sheffield's Megatron: David Richards

The Victorians put it there. In the 1860s the Midland Railway needed a direct line into Sheffield to replace an awkward branch connection from Rotherham Masborough, and the obvious route ran through the Sheaf Valley. A river was in the way. So they entombed it in brick culverts and built their station on top, and when the trains started running in 1870 nobody standing on the platforms had any idea what was rushing under their feet.

Most passengers still don’t, though a grated lightwell built into Platform 5 now lets the inquisitive look down at the water.

What struck me underground is that none of it is crude. The great parabolic arch, three bricks thick, was designed to withstand the weight of trams crossing Exchange Street as well as to swallow floodwater. This was the foundation on which modern Sheffield was built, and it went from plan to platform in a decade.

Before anyone holds that decade up as a rebuke to modern Britain, though, the ledgers deserve a look. Brunel told investors the Great Western Railway would cost £2.5 million and spent more than £6 million. Parliament passed 272 railway acts in 1846 alone, at the top of a mania that ruined thousands of small investors, and the navvies who dug the Woodhead Tunnel died, reportedly, at a higher rate than soldiers at Waterloo. Victorian speed was subsidised by people who never got a vote on it.

The river got no vote either. Bury a watercourse and you abolish its floodplain, which is fine until the weather has other ideas. In December 1991 the Sheaf backed up and flooded the station, halting services on a main artery of the regional economy; the tree branch it dumped on Platform 5 was kept and given a commemorative plaque.

Keeping the 750-metre culvert clear now falls to a £3 million Environment Agency screen at Granville Square, while over at Castlegate the council is demolishing a 1917 culvert altogether, daylighting the Sheaf to make a park that can hold floodwater. The rule the Victorians never wrote down: skip the environment’s invoice and you settle it a century later, with interest.

And yet. Anyone who concludes that caution is free has not read the other column of the ledger. The Victorians built first and posted the bill to their great-grandchildren; we send the bill before the building starts. A passing loop takes a decade of consultation. HS2 shed its limbs one assessment at a time, and the grid connections our AI data centres queue for can take longer to approve than the entire station took to build, river and all. Every reservoir we fail to dig lands on the people of 2126 just as surely as the culverts landed on us, except that they will get nothing in exchange.

Bill Drummond of The KLF painted a question on the culvert wall down there: “Is the river really beautiful or is it just the gradient of the land?” I came up blinking into the daylight with a different question, which is whether Britain can still build anything important and leave something worth inheriting at the same time. We managed the first half 150 years ago and have spent a fortune on the consequences. At the moment we manage neither.

When you read this on Friday morning, trains will be pulling out of Sheffield above a hidden river, proof that a serious country has to hold two thoughts at once: build the thing, and remember who settles the account.

David Richards MBE is managing partner of Yorkshire AI Labs