According to BBC reports:
The most authoritative data comes from the Annual Survey of Hours and Earnings 2012 by the Office for National Statistics.
It shows that median weekly earnings before tax were £506 in the year to April 2012. Men earned £546 a week, while women earned £449.
Median annual earnings were £26,500.
However, there was substantial variation across the UK. The highest median weekly earnings were in London, at £653. The lowest were in Wales, at £453.