Sir Mike Tomlinson said parochial considerations thwarted the taking of decisions needed to make improvements.
He told the BBC News website that accountability could be through a board with a wide skills base, as in Hackney.
Sir Mike is retiring after five years chairing the non-profit trust that runs education in the London borough.
"I think it would be very, very difficult for anyone to say it hasn't worked," he said in an interview.
"Clearly it was from a low base but, that said, the improvements have been considerable over the five years and have been sustained."
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