Citizens of the European Union will be given the right to vote in British elections according to Daniel Hannan, who in WhatsApp messages obtained by the Guardian has told his fellow Conservative MEPs that he has been shown details of the government’s Brexit plans that would enfranchise EU citizens currently living in Britain.

It’s not clear whether that means merely the continuation of the existing rights of European citizens to vote in local elections, or an upgrade in the rights of European citizens to match those enjoyed by Irish and Commonwealth citizens, who can vote in not only local elections but general elections as well.

The United Kingdom has always had a pretty generous franchise as far as longterm residents of the country are concerned, compared to almost everywhere else in the world, though British expatriates get a comparatively raw deal compared to diaspora communities of other countries. One striking feature of in British politics in the postwar period is that the politics of the franchise have largely non-partisan: unlike the battles over extending the franchise in the 19th and early 20th centuries.

But that has begun to change, with the Conservative Party after its 1997 defeat beginning to flirt with a series of measures designed to tilt the electoral balance in their favour. The 2017 Tory manifesto contained a series of proposals which Conservative MPs tend to believe (albeit in some cases incorrectly) would advantage them at elections: tightening rules on what paperwork you need with you to vote, changing electoral registration rules, and expanding expatriate voting rights.

The Opposition parties have been fairly slow to do the same thing. (The increasing forward march of “votes at 16” in all parties, including the Conservatives, has a lot more to do with the fact that while most 16 to 18 year olds are not bothered that they cannot vote, the 16 to 18 year olds who join political parties care a lot about it and agitate about it very effectively.)

There were some measures in the Liberal Democrat manifesto to introduce special constituencies for expatriate voters, but none of the Opposition parties are as yet backing an expansion of the franchise to give European citizens who are longterm residents the same voting rights as Commonwealth citizens. As Hannan notes, enfranchising European citizens, most of whom are not wild about Brexit or the current government’s handling of it would, at the moment “significantly bolster” the anti-Conservative part of the electorate.

In general, however, as well as being a terrible reason to tinker with electoral rules morally, parties that try to change the way elections operate to advantage themselves tend to end up looking pretty stupid sooner or later, as electoral coalitions are in constant flux, and rule changes designed to advantage you today may well lock you out of majority government tomorrow.

Just because it’s a bad idea, however, doesn’t mean that political parties won’t keep doing it. And the changing status of European citizens after Brexit may simply be the beginning of a period in which the question of who can vote in British elections again becomes a live political issue.