Police are investigating claims a woman was raped in the overnight queue for the Wimbledon final on Sunday.
Dozens of tents were set up in Wimbledon Park as hundreds of tennis fans waited to buy tickets to see Andy Murray on Centre Court.
Scotland Yard said a 30-year-old man was arrested and bailed over the alleged attack.
More top news
The threat level has been raised to critical by MI5's Counter-Terrorism Analysis Centre.
Sam Allardyce has quit as manager of Crystal Palace and retired from football management.
Authorities named Salman Abedi as the suspected attacker who detonated a bomb at the Manchester Arena.