The former home secretary has just had the promotion of a lifetime. As of Wednesday, she is officially Britain's prime minister. Much has been made of the fact that she's a woman.It is only the second time in Britain's history that it has had a woman prime minister, and after centuries of being governed by men, it is still a historical achievement for Theresa May to head into No10.Yet as the initial buzz wears off, people are starting to ask: just how much will May do for women?Will she be another Iron Lady (Margaret Thatcher famously only promoted one woman to her cabinet in 11 years and was said to be the woman who smashed the glass ceiling and pulled the ladder up after her), or will she embrace gender equality?The only way to really know what May will do for women is to look at her past. Unlike her leadership rival Andrea Leadsom, who pulled out of the race on Monday, May has had plenty of years in power.She has been an MP since 1997, home secretary since 2010 (a record number of years in the notoriously challenging role), as well as holding a number of shadow cabinet roles.It means she has had almost 20 years to use her influence to better the lives of women.In 2005, she co-founded Women2Win - a Conservative Party group that supported David Cameron's commitment to select more women to fight winnable seats and elect more Tory women to parliament.And in 2010, she was appointed minister for women and equality (alongside her brief in the home office). It was a role created by Labour's Harriet Harman in 2007 and May was the first Tory to hold it.Yet after just two years - in a move that her critics saw as a lack of passion for women's rights - she stood down. Perhaps it was not her best move. But in recent years, May has proved otherwise. As home secretary, she has focused on traditionally "unsexy" issues affecting girls and women - the sort most politicians stay well away from.In 2014, the UK hosted the first Girl Summit and May was heavily involved. She announced positive measures to help survivors of female genital mutilation and crack down on the illegal practice - even persuading Cameron to pledge his support. She announced a £1.4-million government programme and spoke so passionately that the audience was brought to tears (I was there.) She has spoken publicly about supporting gay rights but there is still space for to continue evolving At the Home Office, she introduced the law against coercive control to ensure emotional abusers can be punished just as harshly as those responsible for physical domestic violence. On top of that, she set up a nationwide inquiry into how the police deal with abuse.May has also supported other important gender laws, such as the shared parental leave ruling that came into place in April last year, and spoke of the need to ensure women are in work: "If we fully used the skills and qualifications of women who are currently out of work, it could deliver economic benefits of £15-billon to £21-billion per year."She also voted to remain in the EU - which offers benefits for women such as the EU pregnant workers' directive that helps mothers in the workplace.But her record is not spotless. She voted in favour of same-sex marriage in 2013, becoming one of the first major Conservative members to do so. But prior to that, she voted against reducing the age of consent for gay people and against civil partnership.Her views on LGBTQ issues have been referred to as "an evolution", and she has since spoken publicly about supporting gay rights - but there is still space for May to continue evolving.Her work on equality so far has been important, despite a few shortcomings, but it will be now - as she leads the UK out of political turmoil - that we will see her true colours. Let's hope they include every shade of the rainbow...