Sainsbury's has been named as the sponsor of the British Anniversary Games in the Olympic Stadium in July.
The three-day event includes the British Athletics London Grand Prix and a one-off Paralympic event.
Tickets go on sale on Friday.
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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.