Hamish McRae: The real worry is how have we fallen so far behind the rest of the world

Our system is at best in the middle of the global pack and at worst it is slipping down it

So for the first time school exam results have slipped. Last week we had a fall in the numbers of students getting As and A*s at A-level and now we have a fall in the top grades at GCSE. But can that really be right, or are exams being marked more severely and the decline a reaction to many years of grade inflation?

Well, for anyone who thinks that what matters is not whether you can pass an exam but whether you have a good general education, there is an international study which enables us to cross-check UK student performance against other countries – the Pisa study, which has nothing to do with the leaning tower, but stands for or Programme for International Student Assessment. Started by the OECD back in 1997, with the first results being for 2000, it runs at three-year intervals so we now have results for 2003, 2006 and 2009.

It is huge: in the latest round it tested nearly half-a-million 15 to 16-year-olds from 74 countries. The aim is not to measure how well they can remember and reproduce what they have been taught but rather how well they can function in three areas: reading, maths and science.

So how well do we do? I am afraid the news is not good. Back in 2000, when the main focus was on reading, the UK was ranked 7 out of 30 countries. We were excluded from the 2003 results because we submitted too few responses for our results to be accepted. In 2006, when the focus was on science, we were down to 9th out of 30. And in 2009, when the number of countries and regions was expanded to 74 to include the emerging economies, the UK was 16th in science, 25th in reading and a depressing 28th in maths.

Who was top? On all three categories it was the students in Shanghai. But even within the developed world we seem to be slipping and are way below Finland, which is the best in Europe and Canada and New Zealand. We are now way below Germany in all areas, whereas nine years ago we were above them.

Now it may be that the early results flattered the UK, so we may not have lost as much ground as it would seem. But while we have some great schools, the UK system as a whole is at best about the middle of the global pack – and at worst, slipping down it. Of course, exams are only exams. What matters most is not whether our A-level and GCSE performance is getting better or worse, but whether our young people can compete against their contemporaries in the rest of the world.