Keeping my tin hat on from last week’s column on low traffic zones, let’s turn to the second hot transport topic of the month: the surprising decision by the Government to greenlight the Stonehenge Tunnel.

Back in January, a detailed report by the Planning Inspectorate was delivered to Grant Shapps. The report was finally made public earlier this month, and rather than supporting the Government’s decision, it recommended exactly the opposite.

The key section of the 550-page report is on the cultural and heritage impact. The inspectors quote the Government’s own road building guidelines, stating: “Where the proposed development would lead to substantial harm to or total loss of significance of a designated heritage asset, the Secretary of State should refuse consent unless it can be demonstrated that … is necessary in order to deliver substantial public benefits.

The Planning Inspectorate concluded the project would lead to “substantial harm to the significance of the designated heritage asset” and “considerable harm to landscape character and visual amenity”. The economic benefits of the project, by contrast, are considered, “moderate”.

Even these are questionable. According to Highway England, the tunnel would improve travel times by 4.8 seconds per mile for a 100-mile journey. That’s hardly an earth-shattering change for £1.7 billion. And as anyone who has driven the A303 to the south-west knows, that still leaves plenty of single lane carriageway to sit behind a tractor on.

Earlier in the week, I caught up with historian Tom Holland, president of the Stonehenge Alliance, who oppose the scheme. Tom grew up locally and described an affinity and affection for the landscape since childhood. Preferring a longer tunnel that avoids the site altogether, he describes the shorter version as ‘the worst of both worlds’.

Once the tunnel has been dug, there is no going back. There’s the potential loss of up to half a million artefacts in the excavation. There’s the fundamental altering of an ancient landscape, whose secrets we are only beginning to understand. What makes all of this even worse is the tunnel’s shelf-life: while Stonehenge has been there for five millennia, the life-cycle of the tunnel is a mere 100 years.

Talking to Tom, it felt as though the argument boiled down to a battle of two competing cultures of history: the current custodians who have an eye on present-day tickets sales and selling a sanitised experience; and the archaeologists and historians more intrigued in understanding generations past and by preserving it for future generations.

There are only six weeks allowed for a challenge to the decision. I really hope the powers-that-be think again, to find a way to dig themselves out of making an irreparable mistake.