Pedagogy is a difficult word, and not just in terms of pronunciation. The quality of classroom teaching is the most important aspect of any plan to improve education standards. But, in the UK at least, it has been the hardest factor to prioritise.

Data released on Tuesday by the OECD, the Paris-based club of mostly rich nations, revealed that the performance of the UK’s schools is “flat in a changing world”. The Pisa survey shows there has been little change in the UK’s ranking during the three years since the last international test results were published, which are taken at age 15 in order to compare standards across the world in reading, maths and science.

In science, the UK managed to improve, climbing from 21st to 15th place in the table of 70 participating nations, but stagnated at 22nd for reading, and 27th for maths is disappointing for a nation with a successful education exports industry (think of the overseas students sent both the UK universities and private schools, swelling the coffers of both).