Readers of a certain vintage may remember the early 1980s British rock band Spinal Tap, whose doomed attempts to break America were documented in a 1984 film.

Along the mishaps to befall the group was a disastrous performance of their iconic song Stonehenge: rather than an eighteen-foot model of the stones descending from the ceiling, a misread drawing left the band performing around an eighteen-inch replica.

Meanwhile, in other badly-conceived Stonehenge projects news, last Friday saw the Transport Secretary Mark Harper deciding to give that controversial tunnel another bash.

This, you may remember, was first mooted by David Cameron and Nick Clegg back in December 2014, promising drivers (and floating Southwest voters in the upcoming general election) a dual carriageway from London to within fifteen miles of Land’s End.

Cameron, with his uncanny political antennae (see also Brexit, Greensill), told the world the plan had ‘unstoppable momentum.’

Eight years later, the Stonehenge Tunnel has so far been momentum-less and very much stoppable. Grant Shapps approved it in 2020, despite the Planning Inspectorate writing a 550-page report telling him it was a bad idea.

The government were then taken to the High Court by campaigners and lost, the judge deciding Shapps ‘acted irrationally and unlawfully.’

But be it Rwanda or Stonehenge, this government sees such legal rulings as mere irritation, before going ahead and doing what they wanted to do in the first place.

Shapps’ successor Mark Harper has therefore gone back to the original evidence, promised that this time he has thought about it really, really carefully, M’lud, and despite all the evidence against has decided to proceed with the tunnel anyway.

What has changed since 2020 to mean that the economic benefits of the scheme now outweigh what even Harper’s own ruling describes as ‘harm as a result of the development to cultural heritage and the historic environment’?

I’ve read the 64-page ruling and the short answer is, not very much at all. UNESCO still think it’s a terrible idea. The time saved on the way to Cornwall is still a handful of seconds per mile.

As for the economic impact, that remains pretty marginal at best. Back in 2017, the National Audit Office looked at the financial benefits of the tunnel (then priced at £1.5 billion, now £1.7 billion).

They concluded the tunnel would create just £1.15 for every £1 spent on the scheme. They noted, somewhat drily, ‘given our experience of cost increases on projects of this kind this ratio could move to a … negative value.’

HS2, anyone? Mark Harper’s arguments have all the mathematical literacy of the Spinal Tap guitarist, whose amplifier famously went up to eleven because it was ‘one louder’ than anyone else’s.