The Chancellor has announced that the Northern Line will be extended to Battersea, as part of his Autumn Statement.
George Osborne also announced £1 billion of investment in the country's roads, including upgrades to the A1, the A30 and the M25.
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David Cameron said the Met proved it can "do more with less" and declined to criticise the Mayor of London for his water cannon spend.
A group of disabled activists threw toys and balls at him as he entered the conference.
A wet start to the week and the unsettled weather is set to continue over the next few days.