The BBC reported yesterday that the (Labour) Shadow Cabinet had decided to oppose the legislation to hold a referendum on whether to elect MPs by the Alternative Vote (AV). How hypocritical! How unprincipled! The Labour Party was the only party to promise a referendum on AV in its election manifesto less than three months ago. Now it is the first party to oppose the very legislation it had promised.

I suspect that its main motive is to try to split the coalition and bring it down. Of course, Labour MPs would prefer to be in Government and, indeed, many Liberal Democrats might have preferred to share power with Labour than with the Conservatives, but the voting arithmetic was not right for that. The people spoke and gave more votes and seats to the Conservatives than to Labour.

However, Labour's stated reason for opposing the legislation is that the Bill links the AV referendum to reducing the number of constituencies and equalizing their electorates. If Mr Cameron is serious about holding the referendum and keeping the coalition together, he should separate the referendum legislation from the other. Then, either Labour will support the referendum legislation and it will be passed or the party will be shown to be really unprincipled.

There also some unprincipled Conservative MPs who threaten to vote with Labour against holding the referendum. Although they are entitled to oppose AV itself, they are not entitled to renege on their party's agreement with the Liberal Democrats. If they expect Liberal Democratic support for some Conservative policies, they must support the referendum legislation.

Conservatives who oppose the coalition should also consider the voting arithmetic. The people did not give them enough votes or seats to form a Conservative Government but, in coalition, they can get some Conservative policies through IF they support certain Liberal Democrat policies such as the AV referendum.

They may think that, if the coalition falls, Mr Cameron can call an election and sweep to one-party power but I doubt it. Voters may well blame the Conservative Party for breaking the coalition agreement and punish it in the polls. In any case, the public still seems to distrust politicians and would be reluctant to give total power to one party.

The bottom line is that the only legitimate way to oppose AV is to oppose it in the referendum itself. MPs should no more decide how they are themselves elected than bankers should decide what laws should control banking. It is deceitful, underhand and undemocratic to try to stop the referendum being held; it reeks of desperation. Let the referendum be held and trust the people to decide.