The London Assembly is due to vote this afternoon over the Mayor's plans for affordable housing. Members are currently debating how much landlords can charge tenants across the capital.
The changes would mean that rent on new affordable housing is fixed at 80% of the market rate. Critics say that would make some new properties for people on low and modest incomes unaffordable.
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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.