Two high-profile supporters have deserted the Labour Party over the new 50p tax rate for people earning more than £150,000 a year and the e-mail smear scandal.

Two high-profile supporters have deserted the Labour Party over the new 50p tax rate for people earning more than £150,000 a year and the e-mail smear scandal.

Leading QC Paul McBride and lingerie tycoon Michelle Mone have both withdrawn support, with Mr McBride saying Labour was "serially mendacious and incompetent".

He switched allegiance to the Conservative Party and will speak at its annual conference in Perth next month.

Mr McBride, 44, said: "I have been a Labour supporter all of my adult life. However, I now find myself in a position where I can no longer support a party that is serially mendacious and incompetent, especially in domestic affairs. Wednesday's Budget showed that Labour has been in power for too long. It's a party that now relies on smears and fears rather than policies, persuasion and hope."

The lawyer, a former card-carrying member of the party, has been a regular at Labour fund-raising events in Scotland for the last decade and was a noted supporter of the New Labour project. He said: "My primary feeling is one of disappointed because I still have a fondness for the Labour Party. However, it's the government of the Mary Celeste, floating along in the fog for the next 14 months until it eventually crashes into the rocks and the Conservatives win the election."

Ms Mone claimed the government risked alienating business and damaging the economy. She branded the 50p top rate of tax "a disgrace" and claimed entrepreneurs who had taken big risks to build up their businesses were being punished. Ms Mone, 37, said: "I used to be a Labour supporter but I'm not anymore."

A Scottish Labour spokesman said: "Mr McBride and Ms Mone might be upset with the increase in tax for people earning over £150,000.

"However, the vast majority of Scots support that policy."

The Tories also claimed a high-profile defection by a Liberal Democrat general election candidate yesterday. Norsheen Bhatti, who had been selected by the LibDems to fight the "safe" Tory seat of Chelsea and Fulham, said her former party was "drifting into the wilderness" under Nick Clegg's leadership.

In her letter of resignation, the former assistant to Paddy Ashdown as party leader told Mr Clegg that his party was no longer "representative of the people and views of all members of British society".