In 2005, the UK was the 4th largest economy in the world. China overtook in 2006, France in 2008 and Italy in 2009. So now the official figures suggest that we have dropped to No7 (although I still have some doubt about the Italian figures that are incorporated into this analysis). Projecting forward, the combination of economic growth and population growth, plus a likely rising real exchange rate mean that Brazil and Russia will overtake us sometime soon, perhaps in 2012. India will almost certainly overtake as well, though probably not till 2015. But it also looks as though Canada could, if demand for natural resources continues to rise strongly, catch up and surpass UK GDP around 2015 as well. Even Australia is likely to have overtaken by 2020.

So in a decade, the UK could have dropped from being number 4 in the world to being outside the top ten at number 11 in 2015.

Since most other European economies are likely to do nearly as badly, it is probable that our relative position in the EU will not change much from now on. But it seems reasonably certain that within a decade the UK could move from largest economy in the Commonwealth to the third or fourth largest.

Does this matter? Well in many ways no. In the real world there is no league table, no relegation or promotion, no Sky TV payments to lose out on and even no balloon payments to cushion the fall. And these are only forecasts which would change if trends in GDP, inflation or particularly exchange rates start to change. But there will probably be some psychological implications.

Many Britons are only now getting used to no longer having an Empire on which the sun never sets. Even after the end of Empire, the world’s political agenda continued to be set by people with broadly the same cultural framework as the British. But some of those who are increasingly setting the world agenda have a degree of post-colonial resentment against the British.

Perhaps the area where this will be most noticeable will be on the diplomatic front. It will be difficult to maintain the UK’s current high diplomatic profile when we are no longer in the world’s top ten. Can we maintain a permanent seat on the UN Security Council?

I’m not sure that public opinion in the UK has yet caught up with the potential impact of this change. Among other things, it means that whether we like it or not, we are going to have to be prepared to put up with economic, political and social decisions that are made internationally not only in other countries but quite likely in countries which have very different approaches to – for example – human rights. Adjusting to this change could prove quite traumatic.