So if 271,259 is around 4.2% of the population of the UK, the total population of the UK must be around 271259*100/4.2 = 6,458,547. This is a tenth of what it actually is (64.6 million mid-2014 estimate by the Office for National Statistics).
I could have spotted that the number was an order of magnitude out at age 11 when we were taught about percentages in maths lessons by Mr Powell. Why is it that the sub-editors of newspapers are so strong on literacy but so weak on numeracy?
I bet this wouldn't have happened in The Economist...