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.
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The high of 35C was recorded on a Bakerloo line train between Piccadilly Circus and Oxford Circus at 2pm.
Weather forecasters say temperatures could reach 35C, beating the previous record of 34.6C in the scorching summer of 1976.
After years of political manoeuvring over the future expansion of Heathrow Airport, there has been an important development this lunchtime.