David Cameron defends drive to get women into Parliament as row continues

The Tory leader rejected claims that he was in favour of "politically correct nonsense" and said that it was vital for the party to look like the modern Britain it hoped to represent.

Mr Cameron threw his weight behind Ms Cash as she came under fire publicly for the first time from local members of Westminster North Conservative Association.

Ms Cash sparked a furore last week when she dramatically quit her candidacy following bitter in-fighting in the local party.

Ms Cash, a 40-year-old pregnant barrister, only reinstated herself after her local stalwart Amanda Sayers agreed to step down as party president in the key target seat.

Mr Cameron, who is friends with Ms Cash and an Eton contemporary of her husband Octavius Black, made a staunch defence of his strategy of getting "A list" candidates onto Parliamentary selection shortlists.

This weekend, Surrey East Conservatives selected entrepreneur Sam Gyimah for the party's sixth safest seat in the country. Mr Gyimah, whose family are Ghanaian, was selected despite protests from a local Tory councillor that Conservative HQ was trying to impose a "black candidate" on the area.

Mr Cameron defended the selection of both Mr Gyimah and Ms Cash. "The Conservative party has demonstrated that this is important, that we are a more representative party," he said.

"This is not some politically correct nonsense. It's about being a really effective political party. How can we really say we are a party for everyone if our party is not representative of all those different voices and people in our country.

"It's not about some mathematical representation. It's about making sure the Conservative Party is having a conversation within it between people of different colours and faiths and backgrounds."

However, the row over Westminster North continued as former party chairman Mrs Sayers broke her silence over the affair and critics said Ms Cash had not been "pulling her weight" on the campaign trail.

Mrs Sayers strongly denied allegations that Ms Cash's pregnancy had been a factor in local criticism of her candidacy. "I utterly deny these allegations. I was totally supportive of her during her pregnancy," she said.

Barbara Schmeling, former deputy chairman of the association, resigned in protest at the treatment of Mrs Sayers. She said the conflict centred on Ms Cash's tactic of focusing on Labour-held areas rather than the more well-heeled Tory voting areas of the constituency.

She said: "The dispute was never about Joanne Cash having a baby. This was all a disagreement over election tactics.

"We wanted a plan to get out our core vote. Joanne wanted to spend a lot of time in wards she cannot win."

Susan Burbridge, a Westminster City Councillor, released a letter to Mrs Sayers that said: "I do not want [candidates] getting seats because they have friends and husbands in the right places".

She added: "There are many who feel that Joanne has not been pulling her weight. Wards have noted the times we have seen [Ms Cash] on our streets and councillors how absent she has been from group meetings."