John Payne, who was a Cornwall county and district councillor before Labour's wipe-out at this month's local elections, said its "neo-right" direction, the advent of a unitary council in Cornwall and the expenses scandal prompted him to resign from the party's membership.
A self-styled "Bevanite socialist", the 61-year-old from Penzance was one of only a handful of Labour councillors in the county and the sole elected Labour representative in Penwith district.
He said the post-1997 New Labour and its "lack of care for people" had followed "a neo-right social democratic path, with its only achievement being the national minimum wage".
Mr Payne added: "Labour is nothing like the party I joined in the Sixties – it has sacrificed principle for power. I had great difficulty because primarily I'm a socialist. They are not.
"They have broken so many promises, particularly the 1996 promise to restore the link of pensions to average earnings. They haven't done so and show no sign of doing it."
Mr Payne, a district councillor for 15 years and county councillor for eight, added that the Labour Government sided with the Liberal Democrats over the creation of a unitary council in Cornwall, a move which saw the district councils scrapped.
He said it did not consult the five Labour councillors at county council level.
Mr Payne, who campaigns for benefit claimants struggling to get public funds they are due, added that the exposure of MPs' expenses showed to him that their primary motivation was "greed".
"The local election was the final straw. It was the attitude of the general public and the way they perceived politics. I have seen distrust before but not outright hostility."
Mr Payne, who intends to stand as an independent at the next local elections, said he might be persuaded to return to the party if it returned to its "socialist roots", but admitted that was "very unlikely".
"As was the case with Nye Bevan, you always hope. But there was and there is no-one. What's more important now is the grip of power rather than what you do with it. It goes back to Blair's days."
The Labour Party is now wiped out on the county council. In Cornwall, elections to the new unitary authority saw the Tories narrowly miss out on taking overall control.
article copyright WESTERN MORNING NEWS