The recent report I read showed a graph with incomes of working-age people against those of pensioners. It did seem to indicate that pensioners were better off, but while it showed that the average income for working-age people was only about £20,000 it's not as clear cut as that.
Average Salary UK 2016 / 2017. The average salary UK for the tax year ending 5 April 2015 was £27,600. This is a median average and an increase of 1.6% over the 2014 median average which was £27,200. These averages are for full time employees with data taken from the ONS Annual Average Salary Survey.
That figure of £20,000 includes part-time workers rather than full time, so that will skew the stats.