On the subject of British politicians and education policy, I came to the conclusion as a teenager in the 1970s that British politicians were incredibly two-faced about anything to do with education policy. One of the potential constraints on the behaviour of politicians is the idea that when their party does get into office and introduces a reform, their political opponents may subsequently reverse that reform when they form a government. But in the case of education policy this reversal of a previous government's reforms tends not to happen, and the overall effect of this is to move things in a downhill direction.
To give an example, I attended a grammar school from 1968 to 1975 where the grammar school eventually became a comprehensive in 1979. In the late 1960s I remember that some of the grammar school teachers were quietly confident that plans to phase out the grammar school would be scuppered as soon as the Conservatives got into power. But when the Conservatives did win the 1970 general election, with Margaret Thatcher appointed as the education minister, they did nothing to stop or even slow down the comprehensivisation process. I discovered an interesting factoid from the Spiked website in an article "Five things loved by liberals that Thatcher invented" that Mrs T actually closed down more grammar schools than any other education minister:
In her time as education minister in the early 1970s Mrs T was mainly known for terminating a policy where junior school pupils were given a free third of a pint of milk at school (to combat rickets or something). Labour caused a big fuss over this at the time and invented a slogan "Thatcher the milk snatcher". But when Labour won the 1974 general election they did not re-instate the free school milk that they had complained so much about.