More than five million people worked unpaid overtime in 2008, according to an analysis of official statistics.
The TUC today revealed that the total value of unpaid after-hours work across the UK hit a record £26.9bn last year.
Looking at unpublished data from the National Statistics Labour Force Survey (LFS) and Annual Survey of Hours and Earnings, the TUC calculated that 5.24 million people across the UK worked unpaid overtime in 2008.
Londoners faced the biggest hike in unpaid overtime, with an extra 79,000 workers going beyond the call of duty in 2008. The number of people working unpaid overtime fell by 26,000 elsewhere in the South East and by 11,000 in Scotland.
TUC general secretary Brendan Barber said: “After years of progress, the numbers doing unpaid overtime has increased for the second year in a row. This is disappointing.
“But while some of this is due to the longs-hours culture that still dogs too many British workplaces, the recession will now be making many people scared of losing their job in the year ahead and joining the ever-growing dole-queue.
“Inevitably people will be putting in extra hours if they think it can help protect against redundancy or keep their employer in business,” he added.