Labour, Liberal Democrat and Green groups have been urging Boris to drop his planned cuts affecting the fire and police services.
London Assembly Labour Budget Spokesperson John Biggs, who moved the amendment to the Mayor's budget, said before the meeting:
"Boris has a clear choice, he can either cut council tax by one pence a day, or he can freeze it and use the money to keep our fire stations and police front counters open. By axing 12 fire stations and 18 fire engines Boris is jeopardising the safety and security of Londoners."
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Those gathered on the bridge fell silent at 2.40pm - the time the first call was made to police exactly seven days ago.
Simon Lucy, 61, filmed hundreds of hours worth of footage on the London Underground network.
He delighted fans as he started off his performance playing his song 'Ordinary People'