GREENWICH Council's cabinet have unanimously agreed to close down Blackheath Bluecoat school by summer 2014.
Before tonight's crucial meeting staff, parents and pupils marched from Bluecoat to the town hall, holding banners and chanting "save our school".
But just like their responses to the consultation, where 91 per cent of people were against the move, the protests had no effect.
Director of Children's Services Gillian Palmer stressed that the school only currently had 53 per cent of its capacity and was in line for a deficit of £1.5m this year.
She admitted that standards had improved but said that even last year's record GCSE results were below the borough average.
The meeting, which was surprisingly subdued, also heard that a new school planned for the peninsula, but with no current funding or timescale in place, could fill the gulf in Church of England education left by Bluecoat's closure.
Executive headteacher Jeffrey Risbridger spoke passionately on the school's behalf to loud support from parents and pupils who had crammed into the council chamber.
Pointing to the consultation result, he branded the plan "perverse and undemocratic", saying: "It couldn't be clearer that there's no community will in this borough to close Blackheath Bluecoat school."
He asked why a partnership with St Cecilia's had not been given the full three and a half years it was promised to work, and why the school had been offered £35m investment years earlier from the Building Schools for the Future programme.
But one by one, the cabinet members voted for the proposals.
Leader Cllr Chris Roberts said: "The severity of the cuts that would be necessary means it would probably not maintain the progress it's been able to make."
Afterwards, chair of governors David Prescott said the school would be considering its position.
The cost of closure is expected to be £1.61m.