When he eventually does leave Downing Street, education will be seen by a mile as his most enduring domestic policy achievement. He will have accomplished more in this area than any prime minister since Clement Attlee.

When all the mist of claim and denigration is cleared away, Mr Blair will be seen to have achieved, if not a world-class education system, at least primary and secondary education sectors that are immeasurably better than they were in 1997.

They have been the beneficiary of the bonfire of old Labour thinking on education, as well as a willingness to embrace fresh ideas from abroad, mainly the United States, and from the independent sector. Despite the mantra “standards not structures”, it has been structural reform, with the coming of specialist schools, which has lain at the heart of the improvement.

There are now 2,400 specialist schools, nearly 80 per cent of the total of 3,100 maintained secondary schools in England. By most measures of performance -GCSE and A-level results, attendance and “stay-on” rates after 16 - specialist schools have outperformed non-specialist schools.

This is not what the detractors say, but they are wrong. Specialist schools have made a real and material difference to the lives of hundreds of thousands of pupils. Driving this change has been the Specialist Schools and Academies Trust (SSAT). Founded in 1987 under Margaret Thatcher, the trust in its first incarnation helped to establish the first 15 city technology colleges, which are the forerunners of today’s controversial but pioneering academies.

In 1994, the first 50 specialist technology colleges were created from existing comprehensive schools to specialise in teaching the first three specialisms of mathematics, science, and design and technology. Within two years, others were added, including languages, sports and art.

The current name was adopted in 2005 when the Specialist Schools Trust was given the added responsibility of driving forward the academies programme to achieve former prime minister John Major’s target of establishing 200 of these schools within the next few years.

The SSAT is not only spearheading the drive to make all remaining secondary schools either specialist schools or academies: it has also developed an ambitious programme to disseminate learning and best practice across all schools. It has established networks so that schools with different specialisms can cross-fertilise their ideas, and it is developing links with schools in Australia, China, the US, South America and elsewhere.

Leadership courses are one of its most impressive features. Using the expertise of heads and deputy heads, the trust has been far more successful than the National College for School Leadership.

I would urge independent schools to affiliate to the SSAT, as my own school is doing. They will not only gain much from the exchange of ideas - not least about curriculum development and ICT - but they will also be engaged in bridging the worst feature of British education over the past 100 years: the chasm between the independent and state sectors.

It is utterly crazy to continue to allow both sectors to inhabit parallel universes. As soon as proper exchange happens, people will begin to ask, “Why did this not begin to happen in earnest before?”

Not that specialist schools are flawless. In particular, it seems odd to those in the independent sector that so much weight should be given to just one specialism. Independent schools try to be excellent in all the 11 areas of specialism. So the recent move for “high-performing” specialist schools to be allowed to develop a second specialism is encouraging. More in this direction, please.

Anthony Seldon is master of Wellington college, Berkshire