Did those in the New Labour government ever think, as they amassed “intelligence” to back the 2003 invasion of Iraq: “This could one day be taken apart in a public inquiry”? Did they think, “This claim that weapons of mass destruction could reach our shores in 45 minutes — will people one day demand to know how we came to that conclusion”? Possibly.

But post-Chilcot, post-Butler, and in the full knowledge that government decision-making may be scrutinised, civil servants are now, I’m told, keeping careful notes, convinced they’ll be called to give evidence to a Brexit inquiry.

And it’s not just civil servants. Government special advisers fear this too. “We are fully expecting an inquiry,” a Cabinet minister’s aide told me over dinner last week. “It will be welcomed by extremists on both sides but to sensible people too. There have been so many lies, so many misleading statements.”

Of course Theresa May is famously cagey about how choices are made in Number 10. It’s in part why successive DExEu secretaries resigned and why MPs will press her again to disclose the legal advice given for her Brexit plan.

But the adviser argues that two crucial moments equal New Labour’s 45-minute WMD claim. Both had a profound impact on the deal May negotiated, and both were, arguably, misguided calculations made against Whitehall advice.

The first was the triggering of Article 50. She announced this in a speech to the Conservative Party conference in October 2016 with the intention of reassuring Leavers that she — a Remain voter — could be trusted to deliver Brexit. But at a stroke she undermined the UK’s negotiating position, starting the clock before securing a single concession from the EU, either on substance or the sequence of the negotiations of Brexit.

Dominic Cummings, the Vote Leave chief, described it as putting a loaded gun in one’s own mouth. Not only was Whitehall’s advice tossed aside, the source says, some Number 10 advisers were overruled too.

Her second mistake was agreeing to the Northern Ireland protocol in December 2017 — a decision, the aide says, made without consulting the Cabinet or the DUP. Effectively it committed the UK to the backstop (leaving Northern Ireland alone in the customs union and the single market). Gavin Barwell, her chief of staff, told Cabinet ministers that the language in protocol was “meaningless. Just there to move things on.” But it’s a reworked backstop in the Withdrawal Agreement that keeps the UK in the customs union and Northern Ireland as part of the single market. It’s loathed by the DUP and many of May’s MPs and largely why her deal seems doomed.

So did she have legal advice on the backstop? “If not, why not?” The aide poses rhetorically. “And if so, did she ignore it? Or did they lie to Cabinet?”

"Of course, Theresa May is famously cagey about how choices were made inside Number 10"

I put the inquiry suggestion to a civil service friend who confirms some colleagues “are preparing as if there will be an inquiry” and today The Telegraph prints a leaked letter written in October by May’s negotiator, Olly Robbins, carefully detailing his fears that the backstop would be hard to escape. Evidence?

A public inquiry might want to know why the civil service and millions of pounds were tied up creating DExEU and the Department of International Trade (DIT), “instead of, say, preparing impact studies, or tariff weight quotas, or planning WTO schedules.” With DExEU no longer allowed to engage in Brexit talks, what was the point?

Amid the gloom the royals bring cheer

After the 150 royal weddings and noble births, I’d thought coverage of Kate, Meghan, Pippa, Eugenie et al would dissipate and we’d all return to wrist-slashing over politics. Alas, no. As I waded through the papers yesterday I was greeted with “Carole Middleton’s Christmas”, which Middleton begins planning “soon after Halloween”. It includes “wrapping themes”, “dress codes” and a “flexitarian” menu.

Elsewhere there was a compare and contrast on the Duchesses of Windsor and Sussex (both American, both residents of Frogmore — one in life, one in death), and an exclusive on the palace hunting a “mole who leaked news of rift between Kate and Meghan”.

I suppose “palace staff” have nothing better to do now throwing weddings is over, so hunting moles must fill the hours between picking lint from velvet hair bands and slicing open ball invites with golden paper-knives. On the other hand, the royals provide a welcome distraction to millions in these dark times: an admirable public service indeed.

*During our weekly nit-comb, my son — taking a pencil point to anything live that fell from his fringe — wanted to know the vegan stance on lice. “If they can’t live for more than 24 hours off a human head,” he reasoned, “then combing is murder.”

So I consulted a work colleague, whose boyfriend is vegan. His response? “Head lice are c****”.

I relayed to my son that vegans were fine with killing head lice. “What about Buddhists?” he asked. So we FaceTimed a Buddhist friend, who grimaced and admitted that, for her, lice were “the exception.”

At this thought, my youngest daughter burst into tears: “Poor head lice. They have no friends.”