British heir to the throne Prince Charles may have won public support for his engagement to lover Camilla Parker Bowles but he faces a struggle to convince the nation he should one day be king, a poll showed yesterday.

Two-thirds of Britons accept Prince Charles's plans to marry Mrs Parker-Bowles, his mistress during his turbulent marriage to the late Princess Diana, the YouGov survey in the Daily Telegraph newspaper found.

But a narrow majority wants the monarchy to skip a generation, with Queen Elizabeth handing the crown to her grandson Prince William, 22, on her death or abdication.

"He cannot remarry and ascend the throne," Diana's former butler Paul Burrell wrote in the Daily Mirror. "Charles should renounce his birthright and allow Prince William to be heir apparent."

Royal watchers say Prince Charles, 56, would never consider such a move, which would overturn the centuries-old convention of the monarch's eldest son assuming the throne.

Aware of public misgivings over his lover, Prince Charles ruled out Mrs Parker-Bowles becoming queen once he becomes king.

The Telegraph's YouGov survey was conducted within hours of Thursday's announcement that Prince Charles is to marry mother of two Mrs Parker-Bowles, 57, on April 8.

It found 41 per cent would prefer Prince William to be the next monarch, with 37 per cent favouring Charles. A similar poll in November 2002 put Prince Charles on 48 per cent and Prince William on 28.

Early television straw polls, with no element of random selection, found most people were against the marriage.

Questions of the royal succession were overshadowed by newspaper debate over Mrs Parker-Bowles's new title, her wedding dress and the engagement ring.