London prices have risen by 10.9%, according to latest Land Registry figures, the fastest rate since July 2010.
The average price of a home in the capital now stands at £409, 881.
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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.