The boss of Virgin Money has backed calls for a "ministerial board" championing the economic benefits of gender diversity, but said companies must also explain why they have not signed a charter targeting female equality in financial services.
Chief executive Jayne-Anne Gadhia said a move by City regulators to sign up to the Women in Finance charter had forced finance firms to confront the issue of gender equality.
However, she said there were still prominent companies - including two investment banks - that had failed to put their names to the Government-backed charter, which links executive bonuses to gender diversity targets such as achieving a 50/50 split of women and men in senior roles.
Her comments came as she reaffirmed that the UK economy would benefit from stronger productivity if more women were in senior positions.
Speaking at the Treasury Select Committee, Ms Gadhia said: "We have been really pleased with the impact the charter has had and the thing that I have noticed about it that has been so supportive is that the Treasury and the Chancellor - both George Osborne and Philip Hammond - have taken a personal interest in this. That has been very powerful.
"The support of Bank of England Governor Mark Carney when the charter was launched has not gone unnoticed.
"The PRA and the FCA have both signed up to the charter. I think having your main regulators absolutely 100% behind it has meant that financial services companies cannot ignore it.
"I think doing that more broadly at a national level through Government is of course going to make a big difference.
"The one thing that I would say is - despite all of that - we still have companies that have not signed and we should be doing everything that we can to make sure those that haven't explain why they haven't, or sign up."
The most controversial aspect of the Women in Finance charter has been the decision to link diversity targets to bonuses, Ms Gadhia said.
However, she defended the move, saying it provided a clear signal to boards that female equality was a business issue.
Focusing on her own experiences, she said she had encountered challenges while working at other organisations outside of Virgin Money.
She said: "I used to work for Norwich Union, now Aviva, and there was an issue back in 1994 where Norwich Union was asked to take its sales force off the road to do some retraining, and I was asked to project manage the sales force back onto the road, which I did.
"I hoped as a youngish person that I would be able to take a more senior role in that sales team subsequently, and I was told by a very senior person at Norwich Union that 'you have not got the characteristics necessary to lead a sales force'.
"I said 'what is that', and he said 'the two things you are missing are a thick skin and a load of bull'.
"It didn't make me feel it was sexist at the time, but there was definitely an alpha-maleness about that, which I have never forgotten."
She said that during her time at Royal Bank of Scotland (RBS) there was a very male culture and a "pervading sexism".
She added: "I remember a very senior woman being very upset one day telling me that she was expected to sleep with her boss.
"That sort of thing of course means there are issues for women progressing through financial services."