LONDON (Reuters) - British defense minister Michael Fallon quit on Wednesday, the first resignation in a growing sexual harassment scandal that  prompted calls for a wholesale change in the  locker room  culture in parliament. Members of Prime Minister Theresa May s Conservative Party said the first high-profile resignation in the scandal showed it was time for reform at the 800-year-old parliament, where power is concentrated in lawmakers  hands and wielded, often unchecked, over junior aides. The loss of Fallon, described by Conservative sources as a political  Rottweiler , leaves May with a hole in her cabinet, already at odds on everything from Britain s departure from the European Union to the government s austerity agenda. Weakened after losing her party s majority in a June election, May will want to move swiftly to appoint a replacement with as little disruption as possible. In his letter of resignation to May, Fallon, who had apologized earlier this week for repeatedly touching a radio presenter s knee in 2002, said there had been many allegations about lawmakers, including  some about my previous conduct .  Many of these have been false but I accept that in the past I have fallen below the high standards that we require of the armed forces that I have the honor to represent,  he said, offering no detail on the nature of any other allegations.  I have reflected on my position and I am therefore resigning as defense secretary.  May replied in a letter saying she appreciated  the characteristically serious manner  in which Fallon had considered his position and  the particular example you wish to set to servicemen and women and others . The prime minister was expected to announce a new defense minister on Thursday and is unlikely to launch a major reshuffle of her cabinet at a time when she is trying to push forward Brexit talks. Dependent on the support of a small Northern Irish party for a majority in parliament, May will be keen to try to limit the fallout of the scandal, which has prompted allegations of sexual abuse or misconduct against lawmakers across parliament. Sexual abuse allegations against Hollywood producer Harvey Weinstein have prompted hundreds of thousands of women and men to share stories about improper behavior and Britain s parliament - a bastion of tradition - has been no exception. Ruth Davidson, leader of the Conservatives in Scotland, said it was time to break with a culture in politics when powerful people  use positions of power to demand things from others .  The dam has broken on this now, and these male-dominated professions where the boys-own locker room culture has prevailed and it s all been a bit of a laugh, has got to stop,  she told the BBC. Allegations of sexual abuse have ranged from a charge of rape by an activist in the opposition Labour Party by a senior party member, to unconfirmed details of serial  sex pests  on a list reportedly drafted by aides and researchers in parliament. On Monday, May sat beside the leader of the House of Commons Andrea Leadsom as she set out the government s plans to tackle sexual harassment, including measures to enforce a code of conduct and to set up an independent grievance procedure. May has ordered investigations into a report that one of her ministers asked a female secretary to buy sex toys and an allegation her deputy, Damian Green, made an inappropriate sexual advance on a young woman - something he denies. The prime minister, who has long championed the careers of female lawmakers, said on Wednesday that action would be taken when there were allegations and evidence of sexual misconduct.  I am very clear that we will take action against those where there are allegations that we see, and the evidence is there, that there has been misconduct,  May told lawmakers. 