For the British Liberal party and much of the liberal intelligentsia, the referendum on the alternative vote has become a desperate justification for a disastrous misjudgment. Like a couple in a terrible relationship, who think that having a child will save the marriage, or a gambler who thinks he can recoup his losses by staking everything on one spin of the wheel, they believe that the promise of bringing the electoral system of post-colonial Papua New Guinea to Britain will spare them from the consequences of economic folly.

Forget that they are going along with the extremist programmes of fiscal hawks who have already pushed Ireland back into recession. Jobs, public services and a decent future for the young count for nothing when set against the prospect of "reform".

Ah, how that word thrills the liberal heart. The remedying of abuses, the annihilation of anachronistic traditions – what nobler calling is there for the earnest soul?

Not that I deny that the British constitution needs fundamental reform. We have an unelected House of Lords and a hereditary head of state. In the Commons, the first-past-the-post system guarantees that parties can win landslides without a majority of the electorate voting for them. In 1997, Tony Blair secured a crushing majority of 179 on a mere 43% of the vote.

To add insult to injury, the unelected Lords and the unrepresentative Commons cannot do their job of holding the executive to account. Because we draw our national leader from Parliament rather than electing him or her directly, Liberals and Tories are doffing their caps to Nick Clegg and David Cameron in the hope of office and sinecures, rather than scrutinising their policies, just as Labour MPs doffed theirs to Blair and Gordon Brown.

Real reformers have much work to do. But instead of constraining the abuses of an over-mighty executive and unrepresentative Parliament, the liberals will make them worse.

Their "new politics" consists of a backroom deal in which the Liberals accepted a Tory proposal to cut the number of MPs and the Tories accepted the Liberals' proposal for a referendum on the alternative vote.

Too few people have noticed the authoritarian implications of reducing the number of MPs. Like electoral reform, constituencies of equal size sounds like a marvellous idea. But in an attempt to secure party advantage, the Conservatives will rush a process that ought to be handled carefully. The Boundary Commission will not just liquidate 50 seats, it will reorganise the boundaries of hundreds of other constituencies to find new homes for the abandoned voters. Metropolitan commentators dismiss complaints as special pleading from Labour, which will probably lose ground to the Tories.

They do not understand that most people in Britain still live and die close to where they are born. A sense of place and an attachment to their town or city remain central to many citizens' identity. The Tories are instructing the Boundary Commission to forget about local pride and dispense with public inquiries, where voters in Wolverhampton, for example, could object to being moved into Dudley or voters from Portsmouth could object to being annexed by the Isle of Wight.

At their best, Conservatives once understood the importance of the local and the quirky. Cameron is giving up on the Burkean tradition and carving up Britain like a demented socialist planner scoring lines on a map, not just because he may win more seats but because "reform" will also make the Commons easier for the executive to control.

Consider the position of the harassed MP in the new order. He or she will have thousands more constituents. But they will not have more staff to serve them. A grateful executive has taken the opportunity of the expenses' scandal to hack the resources they need to represent their constituents and investigate the state.

More to the point, if Tory MPs object to Cameron's policies, they will find it far harder to combine with the opposition to mount a successful rebellion. The PM is not proposing to match a cut in the number of MPs with a cut in the number of ministers and junior ministers who must toe the party line or lose their jobs. The payroll vote will remain as strong as ever, while the number of potentially rebellious backbenchers falls.

Say what you will about his hunger for power, but Cameron emerged from the coalition negotiations as a formidable political operator. After making sure the public could not vote on or even attend public inquiries to contest his boundary changes, he made certain that Clegg's proposed "reform" would be subject to a referendum he could well lose.

Clegg, by contrast, emerged as a twerp. He was such a pushover he could not even get a reform of the system the public might support on the ballot paper. Instead of a modified version of PR, he settled for the alternative vote, a joke system that does not solve any of the democratic problems Britain faces. Only Australia, Fiji and the guano-rich Pacific island of Nauru use AV. (The Papua New Guineans dropped it and the Fijians are having their doubts.) In New Zealand, when voters were asked what should replace British first past the post in 1992, only 6.6% supported AV. The rest rejected it for the sensible reason that it would not produce a parliament that reflected the views of the country.

As we approach the referendum, I will take great pleasure in watching journalists destroy alleged supporters of AV by reading out their past statements in which they explicitly rejected it in favour of more proportional systems.

Just as Cameron's boundary changes will not limit the power of the executive, so Clegg's AV will not stop prime ministers getting whopping majorities on a minority of the first preference vote. Go back to Blair's landslide in 1997. As the late Lord Jenkins pointed out in his commission on electoral reform, "simulations of how the 1997 result might have come out under AV suggest that it would have significantly increased the size of the already swollen Labour majority". To be precise, it would have swollen it from 179 to 245.

As compensation for economic mismanagement, the liberals' reforms fail to pass two basic tests. They are not liberal. They do not reform.