Given the widespread view at Westminster that green concerns do not really register with the voters, political leaders from both Labour and Conservative are spending an awful lot of time debating and planning changes to environmental policy.

The immediate trigger of interest is of course the outcome of the by-election last week in Uxbridge and South Ruislip. The swing against the government of 6.7 per cent was dramatically smaller than in the Tory wipeout in the other two constituencies contested last Thursday. If repeated across the country, the voting pattern in the outskirts of London would have denied Sir Keir Starmer an outright majority in parliament at the next general election.