A leading member of Steven Norris's campaign team has resigned to join the Liberal Democrats, it was announced on Thursday.

Edward Lord had served as the Conservative mayoral candidate's deputy campaign director, but claimed he could "summon no enthusiasm for the leadership of Michael Howard who remains an unreconstructed authoritarian".

"I have been a loyal member of the Conservative Party for 16 years, but have found it increasingly difficult to cope with the extreme and highly illiberal agenda being pursued by its leadership," he later explained.

"I began actively considering joining the Liberal Democrats earlier in the autumn and my decision was confirmed when Michael Howard was elected Conservative leader and commenced implementing his entirely unacceptable vision of politics.

"I came into politics aiming to be a catalyst for change: to improve things, to create a better more equal society. I always believed the Conservative Party, with its focus on individual freedom, was the right focus for that change.

"It has proved that it is not."

Lord's defection was welcomed by the Liberal Democrat candidate for London mayor, Simon Hughes.

"I am delighted to welcome Edward Lord to the Liberal Democrats," he said.

"It is clear that he feels the Conservatives under Michael Howard cannot represent the best interests of Londoners. The lack of tolerance, lack of inclusion and lack of libertarian values has disenchanted Edward and will turn off voters."

A spokeswoman for the Norris campaign declined to comment on the news.

The defection follows criticism of the Tory mayoral hopeful after he accepted the interim chairmanship of the Jarvis construction firm.

Norris's political opponents said the appointment represented a conflict of interest.