The school, built in 1958, was the first comprehensive in London
Former Labour MP Tony Benn has said a council's proposal to sell a playground belonging to a west London school to developers is "absolutely wrong".
Holland Park school is due to be demolished and rebuilt and Kensington and Chelsea council plans to raise the money for it by selling the field.
Mr Benn said the council wanted to sell the school's playground because land in the area was "extremely valuable".
The council will decide on Thursday if luxury flats will be built on the site.
Holland Park school was built in 1958 and was designed by the same architects who created the Royal Festival Hall.
Mr Benn, who has lived in the borough for almost 60 years, said: "All my children went to Holland Park school and my wife was chair of governors for many years.
"The simple fact is the land is extremely valuable. The council has decided to sell off the land.
"It's absolutely wrong, they're putting market forces above the children."
The local authority plans to sell the land to developers but the proposal has to be approved by ministers.
Holland Park school was the first purpose-built comprehensive school in London and opponents of the proposal believe that the institution should be refurbished but no part of it should be sold.