The ONS says that after three decades of strong growth, real wages peaked in 2009. Since then, inflation has outstripped wage increases in cash terms.
Real wages refers to wages that have been adjusted for inflation.
The ONS has today said that although it is too early to be sure whether there has been a permanent change in the long-term trend, the decline in real wages has now been sustained for three consecutive years.
The figures show median gross earnings in 2009 were £10.97 an hour in current prices, and have since increased slightly to £11.21 in 2012.
However, after adjusting for inflation, the 2009 figure is the equivalent of £12.25 an hour in 2012 prices.
This represents a peak in the real value of pay, with average pay in 2012 figures falling to £11.92 in 2010 and £11.41 in 2011. This represents an annual average drop in real pay of nearly 3% in 2010-12.
The ONS data shows London workers' earnings averaged £15.70 an hour in 2012, down from a peak in 2009 at the equivalent of £17.07 (in 2012 money).
Across the UK as a whole, the data shows the 2012 level of pay was roughly the same in real terms as it was in 2003.
Full-time male employees in the private sector have seen the greatest decline in real earnings since the recession, both for the UK as a whole and for those working in London. In 2012 their average earnings were worth less in real terms than in 2002.
The ONS compared the path of real earnings in the public and private sectors and found the trends are similar, although the increase in the 2002-09 period was stronger in the public sector and the subsequent decline was less marked.
For example, full-time male public sector workers' real earnings averaged a decline of 2.1% a year in 2010 to 2012, compared with a decline of 3.1% a year for their private sector counterparts.
