Today's European and local elections take place against the background of a Prime Minister fighting for his political life and the continuing saga of MPs' expenses. This extraordinary drama has swept aside much consideration of what the elections are supposed to be about, the future of the European Union and the performance of local councils.

Inevitably, the outcome will become part of the Westminster drama, too, as the results are announced over the next few days. But the elections are important irrespective of their impact on the immediate future of a precarious Prime Minister. Britain's involvement in the European Union is no minor matter. It is central to a wide range of pivotal policy areas, from the economy to the environment.

Voters...