Any question answered...

and yes also the average is skewed because there is a minimum that a full-time employee can earn, which is roughly half of the average, whereas large numbers of people are paid two or three times the average, and a few earn ten times it or more.

To avoid skewing the 'average' due to bankers and footballers earning millions, it is usual to give the median income, not the mean, when discussing the 'average'. I think you'll find that most sites giving figures around £26k p.a. are using the median. The mean is actually pretty close to this if you take the national income and divide between everybody, including the kids, annual per capita GDP is about £25k.