Andy Burnham is being urged by female Labour MPs to commit to a 50:50 gender split within his government should he become prime minister in July.

A draft letter from the Women’s Parliamentary Labour Party (WPLP), seen by the BBC, says Labour must lead by example with its own personnel if it wants to be seen as the party of equality.

Demanding that change start at the top, the WPLP writes: “We are asking you to demonstrate this change from day one and address the toxicity and misogyny within our own party and government.”

Labour has never had an elected female leader, whereas the Conservative Party has had three female prime ministers and is currently led by Kemi Badenoch.

Burnham is expected to remove Chancellor Rachel Reeves from her position as the first ever woman in No 11, and the top contenders to replace her are men.

He will also bring back New Labour ally James Purnell as his chief of staff, a position shared by two women under Sir Keir Starmer.

One member of the WPLP suggested it would not be acceptable “to have more Milibands in the great offices of state than women”.

Energy Secretary Ed Miliband is a possible contender for chancellor in a Burnham government. There is speculation that his brother David could return to UK politics as foreign secretary, perhaps via an appointment to the House of Lords.

However, Burnham moved to reassure the WPLP he was an ally at a meeting this week, promising to sack any staff who undermined women in his team.

Labour MPs have complained of feeling undermined by what they call a boy’s club culture in Westminster. They say this has contributed to scandals, structural misogyny, bullying, and a blind eye being turned to reports of sexual harassment.

The draft letter, yet to be sent to Burnham, states: “We have fought very hard to achieve our electoral success only to find that we are battling within our own party to be heard as women.

“Rooms where decisions are being made are often closed to us leading to blind spots in appointment decisions and policy development.

“The tendency of previous leaderships to sideline the voices of women makes us a weaker government.”

In a 13-point plan aimed at removing barriers to gender equality, the WPLP is calling for a female deputy prime minister, as well as a separate first minister of state for women.

It also calls for zero tolerance of bullying or misogyny from No 10 staff and parliamentarians, as well as unprofessional behaviour that diminishes the contributions of women.

The letter also highlight threats to women, particularly female MPs belonging to ethnic minorities, asking for better security and action through legislation to limit online abuse and deepfakes.

The same group put pressure on Sir Keir Starmer to appoint a woman as first secretary of state, a powerful but still vacant role at the top of government.

Harriet Harman, a former Labour deputy leader who served as acting party leader for short stints in 2010 and 2015, has long called for gender equality in the party.

She was brought in as an adviser on women and girls by Sir Keir Starmer following the backlash to Peter Mandelson’s appointment as US ambassador surrounding Jeffrey Epstein, which Harman said would never have happened if women had been involved in decision-making.

Burnham is so far the only candidate to announce a bid to replace Sir Keir as prime minister. In the event no other Labour MP does so, he could become the next prime minister as early as 20 July.

He has praised Home Secretary Shabana Mahmood and is also expected to reward senior northern MPs who have supported him should he form a new government.

They include deputy leader of the Labour Party Lucy Powell and former transport secretary Louise Haigh, who managed his campaign during the Makerfield by-election.

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