David Cameron should be "braver" in setting out distinctive Conservative philosophies, to counteract the political threat of a Brown premiership, a senior shadow cabinet member will argue today.

Alan Duncan, the shadow trade and industry secretary, will warn in a policy speech that Gordon Brown "will ride high and dominate events" for a least some months after taking over as prime minister. The Conservatives cannot afford to rely on Labour's unpopularity to regain power, Mr Duncan will say. Instead, he will argue that the opposition party "must use our new-found confidence . . . we can afford to be braver."