A spokeswoman for the Reclaim These Streets group said it will seek an order in the High Court on Friday challenging the Metropolitan Police’s interpretation of coronavirus restrictions when read against human rights law.
Reclaim These Streets launched an online fundraiser to raise £30,000 that it said it might need to cover potential legal costs on Thursday night, with more than £37,000 raised by Friday morning.
If the group wins its legal challenge it said it would donate the money to a women’s charity.
The vigil, due to take place at Clapham Common bandstand in south London on Saturday, was organised after Everard’s suspected kidnap and murder sparked a wave of collective grief and anger over the safety of women on the UK’s streets.
The suspect currently held in custody on suspicion of Everard’s murder and kidnap is a serving Met Police officer.
In statement tweeted on Thursday evening, Reclaim These Streets said it was “organised by a group of women who wanted to channel the collective grief, outrage and sadness in our community”.
“Our plan was to hold a short gathering, centred around a minute of silence to remember Sarah Everard and all women lost to violence,” the statement added.
Under the current Covid-19 lockdown in England, people are largely required to stay at home and can only gather in larger groups for limited reasons, such as funerals or for education.
One of the organisers of the said there was an “about-face” by the police on the decision to allow the event to go ahead.
Anna Birley told BBC Radio 4’s Today programme that organisation for the vigil began on Wednesday evening, adding: “We proactively wrote to the police and the local council.
“Initially, we had feedback that they were looking at ways to navigate this, that they would be looking at how they could proportionately and appropriately provide community policing to the event.
“And we were in conversation about how we could do that safely so that people could express their anger and their grief without putting themselves or others at risk.
“We then had an about-face mid-afternoon yesterday. We were being put under increasing pressure that individually, we would be at risk for doing so, but as would everybody who attended and all of the women across the country potentially who have been organising sister vigils in their own areas.”
Police can break up illegal gatherings and issue fines of £10,000 for someone holding a gathering of over 30 people.
Reclaim These Streets said it was “always aware of the challenges of organising a Covid-secure vigil, but safety has been a top priority from the beginning”.
It claimed: “When we initially proposed the event, we proactively reached out to Lambeth Council and Metropolitan Police to ensure that the event could safely and legally take place.
“After initially receiving a positive response, we continued to plan and promote the event and continued to update the Council and Police.
“The Metropolitan Police said that they were ‘trying to navigate a way through’ and that they were ‘currently developing a local policing plan’ to allow the vigil to take place and to enable them to ‘develop an appropriate and proportionate local response’ to the event.
“Since this statement, the Metropolitan Police have reversed their position and stated that the vigil would be unlawful and that, as organisers, we could face tens of thousands of pounds in fines and criminal prosecution under the Serious Crimes Act.”
The group said it had taken advice from human rights lawyers who it claimed viewed that “the Metropolitan Police are wrong in their interpretation of the law and that socially distant, outdoor gathering of this kind are allowed under the current lockdown regulations, when read together with the Human Rights Act”.
Lawyers have written to the force challenging their interpretation of coronavirus legislation, the Reclaim These Streets statement added.
Speaking on behalf of the group, Caitlin Prowle said if it was to lose its legal challenge then it would have to cancel the event and explore other options.
She added: “If we lose we will be facing quite significant fines and we will also be putting anyone who wants to come along at risk of fines as well.”
Prowle said that during planning for the vigil the Metropolitan Police’s “tone changed quite quickly” and that the group’s claims on its alleged reversed position relate to correspondence with the force.
The group’s statement concluded: “We’ve all been following the tragic case of Sarah Everard over the last week.
“This is a vigil for Sarah, but also for all women who feel unsafe, who go missing from our streets and who face violence every day.
It said by “forcing us to cancel” the vigil, the police would be “silencing thousands of women like us who want to honour Sarah’s memory and stand up for our right to feel safe on our streets”.
The Met has been approached for comment by the PA news agency.
Meanwhile, Scotland Yard is facing an investigation by the police watchdog into its handling of an allegation of indecent exposure involving the suspect in the Sarah Everard case.
The Independent Office for Police Conduct (IOPC) is to probe whether officers “responded appropriately” after receiving a report that a man had exposed himself at a fast food restaurant in south London on February 28 – three days before the 33-year-old went missing.