Detectives are questioning three men on suspicion of murder after Ryan Harrison, 22, was hit by a train following an altercation at a railway station.
The man, from Woking, Surrey, was with a friend at Guildford station at 11.40pm on Saturday when he became involved in the confrontation which involved a number of other men, police said.
Two 19-year-old men from Guildford were arrested at the scene while a third man, from Cranleigh, handed himself in at a police station in Guildford later.
More top news
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.