Only the most perverse of masochists enjoys GB News. Those of us whose jollies are not obtained by watching dead-eyed controvobots blame two-tier Keir for chemtrails in the Chagos Islands tend to avoid it. But occasionally – and let’s face it, accidentally – it serves up something worth watching.

One such moment came earlier this week when, in the equivalent of Cilla Black calling out Ella Fitzgerald to face her in a karaoke battle, Jacob Rees-Mogg invited Michael Heseltine onto his show to debate him. The topic was the effects of Brexit and European Court of Human Rights membership on migrant boat crossings from France to the UK. Hezza, old enough at 92 to remember a time when normal people actually dressed like Rees-Mogg does now, wiped the floor with him.

When the failed politician turned failed reality show star started to drone on about leaving the ECHR (as both Nigel Farage and the doomed Kemi Badenoch often do), Heseltine told him not to be so silly. “We’ll never solve the migration problem unless we do it on a European scale… seek accord with our European neighbours and pursue a policy designed to cope with the scale of the problem,” he said.

The inability to stop most crossings, he continued, was a “problem that Brexit has delivered. We have absented ourselves from the corridors of power in Europe and the quicker we wake up to that and get back at the table and negotiate in Britain’s self-interest in the forum of Europe, the better chance we have of dealing with it”. Rees-Mogg sputtered that none of this was to do with Brexit at all, but the data seems to suggest some kind of link.

In 2018, before Britain had officially left the EU, just 299 individuals made the perilous journey across the Channel. Then we took back control of our borders and saw nearly 46,000 cross in 2022, a figure that looks like it may be matched this year.

Global refugee pressures and the rise of smuggling gangs have played their part, but leaving the EU has meant leaving the “Dublin III” arrangement that allowed the UK to return some asylum seekers to the first EU country they entered. The UK made 8,500 requests for return under this system in 2019; two years later, having officially Brexited, the number scheduled for return under new arrangements with individual countries had dropped to just 105.

Although Labour is speeding up returns, the diminished risk of removal after Brexit has been an effective recruiter for the people smugglers. So has the effective closure of other routes to claim asylum or to join other family members who may already be working in the UK.

Last month, a leaked recording of a conversation with shadow home secretary Chris Philp appears to feature him conceding that around half of those currently arriving on small boats could have been returned were we still in the EU. “Because we’re out of the European Union now, we are out of the Dublin III regulations, and so we can’t any longer rely on sending people back to the place where they first claimed asylum,” he can be heard explaining.

“When we did check it out, just before we exited the EU transitional arrangements on 31 December 2020, we did run some checks and found that about half the people crossing the channel had claimed asylum previously elsewhere in Europe – in Germany, France, Italy, Spain, somewhere like that, and therefore could have been returned. But now we’re out of Dublin, we can’t do that.”

Despite all the above, right wing hot-takes site Unherd still managed to publish an article this week with the remarkable headline “Brexit is not to blame for channel crossings surge”. Remarkable since the article below it contained zero evidence whatsoever that Brexit was not to blame for the channel crossings surge – or indeed any discussion of whether it might be to blame for it.

But as Michael Heseltine v Jacob Rees-Mogg – the original battle of wits against an unarmed man – showed us, Brexiteers talking nonsense about Brexit and migrant boats is hardly unheard of…