A serving police officer has been arrested on suspicion of murdering the 33-year-old marketing executive.
Sarah Everard, 33, has been missing since departing her friend’s house in Clapham, south London, on Wednesday.
Scotland Yard had asked pubs to check photographic identification to prevent households from mixing on the premises.
Scotland Yard has been accused of sending "vague threats" to the environmental group on the basis of Covid-19 gathering restrictions – from which XR are exempt.
The arrest was described as mirroring "exactly what happened to George Floyd".
A 40-year-old man was also found injured and taken to hospital, the Metropolitan Police said.
Scotland Yard makes a "mandatory referral" to the Independent Office for Police Conduct.
Two men have been arrested on suspicion of attempted murder.
Scotland Yard has said it will not launch a criminal investigation into SPAC Nation - but one alleged victim says she has not even been contacted by detectives.
Graffiti was found on a building near to the North Brixton Islamic Cultural Centre.