By Ray Fleming

TWO-thirds of Britain's Members of Parliament do not represent a majority of their constituents. That is the anomaly which David Cameron will defend by voting No in the May 5 referendum on adoption of the Alternative Vote (AV) system of voting and his deputy Nick Clegg will oppose by voting Yes. Under AV electors indicate second and third preferences if their first choice is not successful and there is not an overall majority winner. Not since the referendum in 1975 on Britain's continued membership of the European Economic Community have members of the Cabinet taken opposite sides in public on a major issue.

That this referendum will be held at all is the result of Mr Cameron's failure to win the last election and his need to form a coalition with the Liberal Democrats whose main condition was reform to the long-established “first past the post” system. It is ironic that the prime minister's main objection to AV is that it tends to lead to unclear election results and the consequent formation of compromising coalitions.

Conservatives also think that AV forces election candidates to temper their policies in order to avoid putting off electors whose votes they may need if they fail to get an outright win. Mr Cameron thinks that AV is “inherently unfair” and Mr Clegg holds the same view of “first past the post”. They are probably both right.