Ms. Criado-Perez said it was “a brilliant day for women.”

But on the same day, harshly negative commentary started appearing on Twitter, a trickle of abuse that at one point grew into a shower of crude and explicit rape threats against Ms. Criado-Perez at a rate of nearly one post a minute. By this week, several other women who had backed her campaign, including at least one member of Parliament, had also been targeted.

“I will rape you tomorrow at 9 P.M.,” read one of the few printable threats by a Twitter user with the handle @rapey1, said Stella Creasy, a Labor and Co-operative Party legislator from northeastern London. “Shall we meet near your house?”

A 21-year-old man was arrested and then released on bail. Police officers in the London borough of Camden investigating the abuse against Ms. Criado-Perez said the Twitter attacks appeared to involve several people posting anonymously, or so-called trolls.

What is perhaps most striking about this reaction, said Caitlin Moran, a columnist for The Times of London and author of the 2011 feminist manifesto “How to be a Woman,” is how little it took to set it off.

“If even a small thing like this, a nice middle-class debate about putting Jane Austen’s picture on the opposite side of a bank note from the queen causes a storm of abuse like this, what will happen when we get to the bigger issues?” she said in a telephone interview.

Herself a frequent target of abuse on Twitter, Ms. Moran is lobbying to make this Sunday a “trolliday” — a holiday from Twitter trolls — urging users to boycott Twitter for 24 hours to protest what she perceives as a lack of responsiveness to the cyberharassment.

Twitter has pledged to create a new button to report abusive comments. But the company has come under pressure from 64,000 signers of an online petition to do more, showing how the same technology that exposed people to the abuse has given them tools to combat it.