The Coalition and the Constitution. By Vernon Bogdanor. Hart Publishing; 162 pages; $40 and £20. Buy from Amazon.com, Amazon.co.uk

ENGLAND, said Benjamin Disraeli, “does not love coalitions.” That remains true: the British retain a passion for kicking scoundrels out and watching removal vans trundle into Downing Street soon after. The British did not consciously choose the coalition they conjured into being last May when they sacked Gordon Brown but declined to hand David Cameron a majority. Leftish voters, in particular, are furious with the country's third party, the Liberal Democrats, for sharing power with Tories. But at least the novelty is wearing off: nearly a year on, multiparty rule no longer feels quite so alien.

A slim new book by Vernon Bogdanor, recently retired from four decades at Oxford plumbing the mysteries of Britain's unwritten constitution (Mr Cameron was a star pupil), argues that these new arrangements are actually more alien and less democratic than voters realise. For one thing, he says, his ex-pupil is prime minister as a result of an inter-party stitch-up rather than voter choice. Now the coalition is planning big changes to the constitutional status quo. Alas, they carry hazards that are just as poorly understood, Mr Bogdanor thinks. The first test will come on May 5th, when Britain is to hold a referendum on whether to change the voting system for general elections from First Past the Post (FPTP) to the Alternative Vote (AV), in which voters rank candidates in numbered order of preference.

In the short term the result will strain the coalition. The Tories want no change, the Lib Dems are campaigning for a Yes. In the longer term, it is a commonplace among the political classes that AV matters because it would hand the Lib Dems perhaps 20 more seats than FPTP, a system that brutally disfavours smaller parties.

Not so fast, says the professor. Firstly, FPTP actually punishes parties with diffuse geographical support (just ask the Tories, who won one in six Scottish votes at the last general election but picked up just one in 59 of Scotland's seats, Labour in southern England and Lib Dems everywhere). Secondly, the only large country to use AV for national elections, Australia, forces voters to rank all candidates. The version of AV being offered in Britain is more like that used in some Australian state elections, which allows voters to “plump” for a single party, and leave all other preferences blank. Where voters can plump for one party, a majority do just that, subverting AV into a version of FPTP.

Yet AV matters greatly, Mr Bogdanor concludes, because it makes co-operation between parties much easier: party leaders would be able to urge supporters to give their second preferences to an allied party. Add that to the slumping support for the two big parties, and coalitions could become the norm.

The book makes a depressingly strong case that the changes being mooted to Britain's curious version of democracy will not do the trick (in addition to querying AV, it poses painful questions about other changes planned, such as fixed-term parliaments and a semi-elected House of Lords). It is less convincing when suggesting how to fix things. Mr Bogdanor favours proportional representation buttressed by lots of direct democracy, from party primaries to frequent referendums and Citizens' Assemblies. That is the stuff of fantasy: there is no appetite for such a system in grumpy, uncivic Britain. Instead, the country faces a string of tinkering changes. The unintended consequences will be many. This shrewd, short book explains why.