England's education system is like the national football team – "better than many, but hardly top-notch", Sir Michael Wilshaw has warned.
And in a fresh attack on Theresa May's plans to allow more grammar schools, the outgoing Ofsted chief inspector said a return to selecting pupils by academic ability was not the answer to raising standards.
In a speech this morning, Sir Michael said there had been huge improvements in the comprehensive school system in the past few decades, but the serious shortcomings that remain have led some to conclude that the system which sees children of all abilities educated together is "broken". This, in turn, had led to calls for a return to grammar schools.
Addressing the Freedom and Autonomy for Schools – National Association (FASNA) annual conference in London, Sir Michael said: "For the most part, England's education system is a bit like its football team – better than many, but hardly top-notch.
"We comfort ourselves with past success, illusory as that might be, dream of future glory, then collapse into despair when we come across superior play.
"This familiar tale of disappointment, however, is misleading in two important respects.
"Firstly, it fails to recognise that our education system has come from a long way back. Twenty years ago, standards were truly dire across the phases, and generations of children were being let down year after year.
'Schools have got a lot better'
"Since the dark days of the 70s, 80s and much of the 90s, schools have got a lot better.
"Secondly, it can tempt us to adopt fanciful and nostalgic solutions while our very real structural problems are ignored."
Sir Michael added: "Let me be clear, for all their faults, our schools have improved immeasurably."
The chief inspector said nothing should be done that would jeopardise the improvements being made in state schools.
There are still problems, he said, such as the achievement gap between rich and poor secondary school pupils, and a "growing geographical divide" in standards after the age of 11 between the North, the Midlands and the South.
"All this has led some to conclude that the system is broken," he said. "Comprehensive schools, they earnestly believe, have failed."
'Selection at age 11 is simply not the answer'
But Sir Michael argued that a return to a grammar school system would be a "monumental mistake", adding: "For the country as a whole, selection at the age of 11 is simply not the answer."
He suggested that part of the reason grammar schools were "back in vogue" was because of a failure to fully reform comprehensive schools.
"Two years ago... I warned that those who were resisting reform, who were refusing to embrace greater diversity in our school system – academies and free schools – would inevitably pave the way for the return of selection," he said. "And so it has proved."