LONDON • A month ago, Mr Michael Fallon was being talked about as a potential successor to Prime Minister Theresa May if she had to be replaced with a caretaker leader.
Now he is the first casualty of the sexual harassment scandal engulfing Westminster, and Mrs May is preparing to name a new defence secretary.
Mr Fallon announced his resignation late on Wednesday, referring obliquely to "allegations" about his private life.
On Monday, he had admitted repeatedly touching a female journalist's leg during a dinner. That was prompted by women speaking out about their experiences in British politics in the wake of the Harvey Weinstein scandal in Hollywood.
Although the governing Conservative Party is currently the focus, harassment allegations - and worse - have crossed party lines in Britain.
Their full scope and reach remain to be seen. In the long run, it could force soul-searching about an endemic problem in politics and the corporate workplace.
"People may imagine that the Prime Minister is in charge of Parliament," said Professor Steve Fielding, professor of politics at Nottingham University.
"They will see politicians, mostly Tories, in the news doing bad things. Unless May can come up with a dramatic and simple solution to a complex problem over which she has little authority, then she will be tarred with it."
In the meantime, she replaced Mr Fallon with party chief whip Gavin Williamson yesterday.
Sex scandals in Westminster are nothing new. But the allegations here are of harassment and assaults, not infidelity.
"There has been this sense that people can use positions of power to demand things from others and that has got to stop," Scottish Conservative leader Ruth Davidson told the BBC.
"It's not actually about sex, it's about power; it's always been about power, and we as elected representatives have to hold ourselves to a higher standard."
There has been this sense that people can use positions of power to demand things from others and that has got to stop... It's not actually about sex, it's about power; it's always been about power, and we as elected representatives have to hold ourselves to a higher standard.
SCOTTISH CONSERVATIVE LEADER RUTH DAVIDSON
Doing the rounds of social media and the inboxes of journalists and politicians is an unverified list of names linked to various sorts of sexual activity - ranging from workplace relationships to affairs to inappropriate approaches towards junior staff. It includes redacted names of high-profile figures, some of whom have gone on the record to reject the allegations against them.
Britain's libel laws, which require a publisher to prove that something is true, mean newspapers have to proceed with caution.
NO SUPPORT FOR VICTIMS
It's not just one party or another; Westminster suffers from sexism and harassment just like the whole of British society. What we lack is modern processes for reporting and for supporting victims.
LABOUR LAWMAKER ALISON MCGOVERN
The stories emerging about Britain's ruling class go beyond the Conservatives, and some are far worse than unwelcome attention or inappropriate requests.
The most serious so far concerns the opposition Labour Party. A 25-year-old activist alleged on Tuesday that she was raped in 2011 by a more senior activist at a party event and then discouraged by a Labour official from speaking out.
"It's not just one party or another; Westminster suffers from sexism and harassment just like the whole of British society," said Ms Alison McGovern, a Labour lawmaker.
"What we lack is modern processes for reporting and for supporting victims."
British politicians trying to address harassment are realising that the set-up of Parliament makes it difficult.
Staff are not centrally employed, and they have no human resources department or code of conduct. Instead, each lawmaker recruits his own office, working as a small business. If a researcher wants to complain about his boss, it is not clear who he can go to.
Mrs May on Wednesday said she wanted a central parliamentary complaints procedure.
But even if she secured agreement to that, the House of Commons itself has few powers to discipline its own members.