Senior Liberal Democrats have accepted that the party may need to resort to all-female shortlists or other tough measures to increase the representation of women and minority groups among its MPs.

The LibDems currently have the lowest number of female MPs of the major parties, with only seven women out of its 57 members of parliament (12 per cent). It's also alone among the three major parties in not having a single black or ethnic minority MP.

Even worse for the LibDems, many of the its female MPs are from marginal seats. The majority of all seven female LibDems combined (17,224 votes) is only slightly larger than Nick Clegg's majority in Sheffield Hallam.

Yet Lib Dems have generally not been in favour of all-women shortlists or other similar mechanisms to increase representation, because it is seen as anti-liberal. Activists have previously voted against the move at its party conference. Instead the LibDem prefers its candidates to emerge purely on merit.

Other parties have taken more official measures to boost the number of women and ethnic minority candidates, however, including famously the Labour party under Tony Blair in 1997, which introduced all-women shortlists.

Now the mood may be changing among the LibDems, many of whom admit to being embarrassed by its failure on representation.

Lynne Featherstone MP, who is also the equalities minister, said at a fringe meeting hosted by The Guardian that she had once considered resigning after the party rejected a move towards all-women shortlists at a previous conference.

"I am wildly off-message in terms of our party on this because I think the women-only shortlists that Labour went ahead with have seen a miraculous step-change, and I take my hat off to them for that," Featherstone said.

"I was so upset with our party (when we lost the vote at Eastbourne) that I was contemplating after a few drinks resigning in the bar," she said. "Then Shirley Williams (the LibDem peer) came up to me, she's my political heroine - and said 'Ms Featherstone, I hear you are thinking of resigning, the party needs women like you' - and it was because of her I stayed."

Featherstone said the LibDems had made a big effort in 2010 to increase its number of women candidates. However "the fly in the ointment is that we didn't win the seats".

The LibDems have recently introduced a leadership programme which they hope will redress the balance both for women candidates and for those from ethnic minorities.

"This is going to deliver women and ethnic minorities at the next election," Featherstone said. "And I can't wait for that day."

Tim Farron MP, who was also speaking on the panel, said that he was "utterly embarrassed" that only seven of the party's MPs were women.

He said:

"Over the years we've had several debates on the crushing lack of women in the House of Commons, and our zero lack of representation from black and ethnic minority communities, and the debates we've always had are about the practical way to create equality and the liberal argument about how people should get there on their own merits," he said. "Frankly I think we're beyond that time."

Admitting that other parties had been able to do "what we've failed to do", Farron, who has been widely tipped as a possible future leader of the LibDems, said that the party needed to take action.

Farron pointed to the "zipping" process adopted by the LibDems in 1998 for the European elections, in which women were put at the top of half of the party lists, with a man second. The process greatly increased the chances of women being elected in greater numbers, and the result was five women and five men becoming LibDem MEPs.

Farron said that "we should look to that" as a possible solution for the House of Commons.

"If I thought (female shortlists) would work… we should do it now," Farron said. "My great fear is that if you want to become an MP in the Labour or Tory party you get yourself put in a safe seat. Small problem for us: we have no safe seats."

Farron said that historically the LibDems have been poor at handing seats from incumbents to new candidates and that without that assurance it would be difficult to bring more women into parliament.

"The leadership programme is trying to help that, because how do you get elected as a Liberal Democrat? It's not by being put in a safe seat, it's by being an absolute nutter who gets themselves elected from the ground up. We need to enable, financially and in terms of confidence, and indeed by rigging the rules for them, a greater proportion of the natters to be women and from black and ethnic minority backgrounds."

Former LibDem leader Paddy Ashdown, who also spoke on the panel, said that the lack of women LibDem MPs winning election to parliament during his tenure was the "biggest failure" of his political career.

"I don't like women shortlists or shortlists for anybody. I find them illiberal and I find them demeaning to those who are put in that position, and I find them potentially insulting."

Interrupting applause from party activists at that point, however Ashdown added:

"The truth is that we have failed at this for too long, and if the leadership programme doesn't work then I think we should be doing this. If this is the only way, through a temporary mechanism, to crack this nut that we have singularly and shamefully failed to crack, then I'll be in favour of it."