David Cameron pledged to “prove to people” over the next few months that the Tories are a credible government-in-waiting, as he celebrated a landmark local elections victory on Friday.

The Conservative leader hailed his party’s best performance in local polls since 1980 as a “very big moment,” marking a “vote of positive confidence” in his party. But he implicitly acknowledged Labour warnings that the scale of the electoral triumph will increase scrutiny of his party as the potential next government.