A number of factors are involved here.
First and foremost, successive governments enjoy an ongoing obsession with further education. They insist that everyone wants to go / is suitable for university, which is arrant nonsense, but they plough milliions of pounds into funding propoganda that continues to fail in its mission.
At the other end of the scale, successive governments ignore nursery education, and treat it with contempt.
Why else would nurseries be staffed with disinterested teenage girls with no motivation or empathy with children, being paid less than they could earn in a supermarket, or the same as they could get for cleaning toilets.
If one government took the brave step of inverting those two education concepts, and put money and training into nurseries, we could have a generation of children who understand the basic concepts of the three R's as they enter school, instead of playing 'catch-up' through their entire time in education, being taught a curriculum that changes like the wind as successive Education Ministers mess with it.
My wife is currently working as an Inspector in schools in Abu Dhabi. There, children are taught science from the age of four, in English, and they thrive.
If the goverment could appreciate teachers for the job they do - and not constantly tell them, and the public, how useless they are, which has gone on for so long that it has become a self-fulling prophesy.
Education is a conversational football for all governments because they see it as a vote-catcher, so they pretend that school is as it was in the 1950's - when their immigration policies have swamped primary and secondary schools with pupils who cannot speak English.
If just one government could treat education with the finance and gravitas it deserves - as the training ground for the next generations, things would improve.
Investing in education is not 'sexy', running down teachers is.
No need to look any further for our ongoing poor showings against the rest of the world.
They care about the future for their populations- we prefer to moan about fast trains and expensive energy.