Tom Peck's Sketch. Poppers debate: How better to talk young people out of experimenting with anal sex than to listen to Keith Vaz talk about it?

The philosopher of science Karl Popper devoted his intellectual life to the theory of falsificationism, the idea that a hypothesis can only be proved true once it is shown it can be false.

So it is right that it should be with this spirit of exhaustive scepticism that you approach the question of whether you choose to believe that – when MPs came to debate the banning of the sphincter-relaxing stimulant that now bears Professor Popper’s name – it fell to Keith Vaz to speak up for its beneficial properties for anal sex, and for the Conservatives’ pre-eminent expert in foreign affairs to “out himself” as a user.

The official Hansard transcript may not be enough to convince you. Nor should my humbly stating that I was there. The video footage on the parliament website might be enough do it. But we can never be fully certain - so it must be true.

Indeed, it is true. It is five years since Crispin Blunt MP, the chair of the Foreign Affairs Select Committee, came out, having been married for twenty years, and only a week since he was bravely interrogating the Prime Minister over the Libyan debacle.

“I out myself as a popper user,” he said. “I would be directly affected by this legislation. I am astonished to find that it’s proposing to be banned and frankly so were very many other gay men.”

The Psychoactive Substances Bill that was being debated seeks to ban all so-called ‘legal highs’, even those that have been shown to do no harm to society, of which laughing gas is one and poppers, or amyl nitrate, another.

“Sometimes something is proposed that is personal to you,” he continued. “And you realise the government is about to do something fantastically stupid and I think in those circumstances you have a duty to speak up.” A statesmanlike sentiment, and one more commonly deployed by MPs to block restrictions to the buy-to-let property market.

There would be further unintended consequences too, with Mike Freer, the Conservative member for Golders Green and Finchley, highlighting the efficacy of amyl nitrate in treating adder bites. For Mr Freer, it is a question of causation.

“If you wish to drink bleach you will be harmed,” he said. “But we are not proposing to ban bleach.” A salient point, but anyone who drinks bleach in search of a good time and ends up surprised to be having a bad one may not find themselves widely mourned by the nation.

With specific regard to the anal sex question, it was Mr Vaz who highlighted that, ‘The government recognises that representations have been made to the effect that poppers have a beneficial health effect in enabling anal sex in men who have sex with men.”

He also welcomed the move to rebrand such substances psychoactive drugs. ‘I’m glad we’re not calling them legal highs anymore,” he said. “That persuades young people to want to try them.’

And in that spirit, if there are any confused young people out there, feeling strange feelings, and fearful of beginning that journey to the outer reaches of their own burgeoning sexuality, how better to talk them out of experimenting with anal sex than to listen to Keith Vaz talk about it?

As he argued against the popper ban, he spoke of his children, who are “20 and 18 and away at university.”

“It is every parent’s worst nightmare,” he said. “That they should be out celebrating after doing their work, they are offered a substance, they take that substance, and they become ill, or worse, they die.”

An unpleasant turn of events no doubt, but can it really be a worse nightmare than your son or daughter going on a night out and ending up having anal sex with a Member of Parliament? That is a hypothesis which we can only hope remains unfalsifiable for as long as possible, but it does happen.