Two people are facing jail for subjecting feminist Caroline Criado-Perez to online abuse following a campaign to ensure a woman featured on British bank notes.

Isabella Sorley, 23, used Twitter to tell campaigner Criado-Perez to "f*** off and die you worthless piece of crap", "go kill yourself" and "rape is the last of your worries".

John Nimmo, 25, told Criado-Perez to "shut up bitch" and "Ya not that gd looking to rape u be fine" followed by "I will find you [smiley face]" and then the message "rape her nice ass", Westminster magistrates court heard.

Nimmo also targeted Stella Creasy, the Labour MP for Walthamstow, with the message "The things I cud do to u [smiley face]", calling her "Dumb blond bitch."

Nimmo, from South Shields, Tyne and Wear, and Sorley, from Newcastle-upon-Tyne, are due to be sentenced at the same court on Friday.

They pleaded guilty to sending menacing tweets on 7 January, admitting they were among the users of 86 separate Twitter accounts from which Criado-Perez had received abusive messages.

Following the court hearing, the 29-year-old student thanked people for their support but warned that Sorley and Nimmo represented a "small drop in the ocean" to the amount of abuse she received in July and August.

She tweeted a statement saying: "I am hugely relieved that these two defendants have pleaded guilty, meaning that there is no need for a trial and for the whole process to drag on longer – it has already dragged on for almost six months, with all the attendant anxiety you'd expect.

"This is not a joyful day; these two abusers reflect a small drop in the ocean, both in terms of the amount of abuse I received across July and August, but also in terms of the abuse that other women receive online – women who have little to no recourse to justice.

"However, I hope that for some people who are watching, this conviction will be a warning: online abuse is not consequence-free. I hope that some people watching will think twice before abusing someone else. There is not much else I can say given there are other cases still on-going."

Sorley was warned by district judge Howard Riddle that it is "almost inevitable" that she would receive a jail sentence.

The judge also told Nimmo, described to the court as a "social recluse" who "rarely leaves his house", that "all options" as to his sentence remained open.

Their abuse took place after Criado-Perez led a campaign using social media and backed by high profile public figures for a female figure to appear on a Bank of England note.

On 24 July, the campaign found success when it was announced that novelist Jane Austen would appear on a bank note in the future.

Alison Morgan, prosecuting, said said the "extreme language" used by Nimmo and Sorley had caused "substantial distress or fear".

"Caroline Criado-Perez has suffered life-changing psychological effects from the abuse which she received on Twitter," she told the court.

"In particular, the menacing nature of the tweets sent by both defendants caused her significant fear that they would find her and carry out their threats."

Morgan added that Creasy had also suffered a "substantial impact" as a result of the abuse.

The court heard that MP responded to Nimmo's message of "Dumb blonde bitch" with the message "That's dumb Dr blonde bitch to you".

"Love it at least u can have a laugh," Nimmo responded, to which Creasy said: "I'm not having a laugh, I'm cataloguing your vile conduct #takebacktwitter."

Sorley was arrested in October 2013 at her home in Newcastle and admitted to police that she had sent some of the tweets, suggesting she had been "off my face on drink" at the time, the court heard.

Paul Kennedy, representing Nimmo, described his client as of previous good character, adding: "He is a social recluse, that is exactly what he is really, he rarely leaves the house but to empty the bins.

"He sits in the house 24/7, he has nothing to do, he claims benefits, he is a somewhat sad individual."