Defeated candidate Susan Press spoke out for the first time yesterday following Yorkshire Post revelations that some party members in Calder Valley were demanding an urgent investigation into the selection process after Steph Booth's triumph.

Mrs Booth's ability to attract a large number of postal votes was decisive in her campaign to become the Prospective Parliamentary Candidate following Chris McCafferty's decision not to contest the seat again.

Ms Press said before she even entered the hustings at Mytholmroyd Cricket Club on April 9 she knew she had already lost because of the number of postal votes cast for her opponent.

Ms Press polled 35 votes to 22 on the night, but thanks to the postal vote Mrs Booth won by an almost 2-1 majority, 95-52.

One of the allegations being presented to the regional Labour Party by Calder branch chairman Paul Clarke is that supporters of Mrs Booth approached party members and helped them fill in their forms.

But Mrs Booth said she thought the number of postal votes was down to the hustings taking place on Maundy Thursday – the start of the Easter break when many people were setting off on holiday.

She added that former Prime Minister Tony Blair and his wife Cherie had phoned to congratulate her saying they were delighted'.

A Susan Press supporter has said that the existing system means postal voting "can make a mockery of the democratic process which the hustings represent" .

It is not just Calder Valley where concerns are being raised. There are also demands for an inquiry into the high number of postal vote applications in the selection of Labour's candidate in the Westminster seat of Erith and Thamesmead.

The south-east London seat is being vacated by sitting MP John Austin and a large number of members have applied to vote by post rather than turn up in person at the hustings on Saturday.

Ms Press said: "The concern is that the rules are open to abuse and I think that's why people are calling for an inquiry in Erith and Thamesmead and Calder Valley.

"There was such a discrepancy between the vote on the night and the postal vote – even if every person in the room had voted for me I could not have won.

"I think the Labour Party has to look at this issue. I have spoken to three members of the National Executive Committee and it is clear that it is something that people are really concerned about.

"No one has a problem with housebound people postal voting, but it was the number of postal votes cast that determined the outcome."

A former Labour MP for Halifax, Alice Mahon, added that as well as worries over postal voting she was also concerned at reports that professional public relations firms were being imported into would-be MP's campaigns, though it is understood this did not occur in Calder Valley.

Of Erith and Thamesmead she said: "I think people must be very worried about reports that PR firms are being brought in for what is supposed to be a democratic process and now it seems 'outside forces' are moving in.

"This is not how it was intended to be. We thought we had a foolproof democratic process."

Regarding Calder Valley she added: "Under the rules postal voting was supposed to be for a specific reason – a member was working away or on holiday, that kind of thing.

"The number of postal votes was very high and I think if they are being manipulated in any way that is not a good thing."

A spokesman for the Yorkshire and the Humber Labour Party said the Calder Valley contest had been carried out under the rules laid down by the party's National Executive Committee and Steph Booth had gained a "clear victory."