He claims leader David Cameron has turned his back on Conservative principles.

As a Lewes constituency deputy chairman, Tam was one of the architects of the party's general election campaign in Lewes in 2005 and is the current holder of the Lewes Conservative's silver campaigning cup for his work in that campaign.

A past Conservative candidate for county and district council, the resident of Streat, near Lewes, has been an activist since the 1970s, although he briefly joined the Referendum Party in 1997.

'I am leaving the Conservative Party because I am a conservative,' he said.

'David Cameron has turned his back on conservative principles and has embraced political correctness, high taxes, and more state control in his misguided new direction for the party.

'I have not changed, but the Conservative Party has moved away from the values which matter to me and to hosts of other voters.'