Something truly remarkable happened last night in the House of Commons: facing a rebellion by pro-Brexit Conservatives in the European Research Group, the government U-turned on plans to ban assault rifles, amending its own legislation to strip references to the dangerous devices from the Offensive Weapons Bill.

Although the United Kingdom already has fairly tight restrictions on who can own and use firearms outside Northern Ireland, and heavy restrictions on how much ammo can be bought, the police have asked for these new restrictions to help get new and dangerous hardware off the street.

There are a couple of really striking political sub-plots here: the first, of course, is that it is indicative of how dysfunctional this parliament has become. The government can’t even – in a country in which support for gun control is near-universal, when a ban has been called for by the police, when there is notionally cross-party support for the measure – successfully ban assault rifles.

But the second is that it is a strikingly bad strategic choice on the part of the following groups: the European Research Group, Theresa May’s government, and Conservative backbenchers.

On the part of the ERG, it risks associating support for Brexit – a political proposition commanding at a minimum the support of 45 per cent of the country – with support for easy access to firearms, a position that in the United Kingdom is associated with far-right wingnuts from the United States. It’s a political position, rather like May’s embrace of ending the fox hunting ban, with the potential to travel far and wide online during the heat of an election or referendum campaign, with potentially disastrous consequences for the long-term political viability of the Brexit project. To my surprise, none of the organised Remain campaigns have tried to piggyback on the association or make capital out of the fact that every leading Brexiteer can now perfectly fairly be described as having opposed measures to remove assault rifles from our streets, but it can only be a matter of time.

As for Theresa May and her government, the Prime Minister was handed a big, shiny gift from her internal opponents. Trying to pass the ban with the support of Labour was a win-win proposition. In the worst case scenario, if Labour had refused to back the bill, it would have associated both her internal opponents and the Labour Party with a highly unpopular cause that will be very, very difficult to defend. In each case it would have reinforced a dangerous weakness in the brands of both sides: on the part of committed Eurosceptics, that there is something eccentric and dangerous about Tory Brexiteers, and on the part of Labour MPs, that their hearts may be in the right place but they can’t be relied upon to “do the right thing” when it comes to crime and security. Every sitting Labour MP in a marginal seat could have had targeted Facebook adverts in their constituency saying they had voted against the wishes of the police and in favour of easy access to assault rifles. There is an open question about whether the Conservatives are better off trying to win back places like Kensington or Battersea or trying to do a bit better in the likes of Bishop Auckland and Ashfield and that often involves difficult political trade-offs. But gun control is popular – wildly popular – everywhere in the United Kingdom.

Or, in the best case scenario, Labour votes with the government and Theresa May would have successfully banned assault rifles. What’s not to like? Instead, May went for Option 3) give your opponents a legitimate reason to put the name of every Conservative MP and the phrase “voted against banning assault rifles” together on one leaflet or shareable video.

But – and here’s the really striking thing – as well as securing the support of the ERG, every Conservative MP went along with the vote. Of course, every Tory MP I have spoken to privately is mystified by the decision, but for the most part, the politics makes short-term sense: they are in safe seats where the issue is not going to cause immediate harm. That said, one can easily imagine how at some future election, any of James Cleverly, Penny Mordaunt or Nigel Huddlestone, either as a boxfresh opposition leader or as Prime Minister, will wake up to discover that a Momentum video on their opposition to banning assault rifles (pegged perhaps to some hypothetical future shooting) has gone viral on Facebook overnight. But it’s not just future prospects. Take say, Jake Berry, Ben Bradley or Jack Brereton, all of whom are in marginal seats, and all of whom opted to vote against banning assault rifles. To repeat: gun control is popular everywhere in the United Kingdom, and assault rifles are popular nowhere in the United Kingdom.

This was a political choice with the difficulty turned all the way down to “casual” and yet somehow it ended up with the Conservatives opting to take political damage.

We haven’t really paid much attention to this vote because of the ongoing Brexit chaos, but I would suggest that we should precisely because of the ongoing stand-off. The underlying assumption that we have about no deal is that it won’t happen because it is politically damaging and ultimately it would be an astonishing failure of political strategy and intelligence if we left the United Kingdom without a deal essentially by mistake. A no-deal exit will be a far bigger political event than voting against banning assault rifles, but that Conservative MPs just failed to navigate a far easier political trade-off is a reminder that we can’t guarantee they will successfully avoid no deal.