A new report from the Trades Union Congress (TUC) has revealed the number of employees working "extreme" levels of overtime has increased over the last ear to some 900,000.
Furthermore, one in five teachers and lawyers were found to be working an additional 17 hours every week, all for no additional pay.
Overall, the number of Britons carrying out ten hours of unpaid overtime in a week rose by 14,000 during 2009, with single women the most likely to be putting in extra hours.
This is despite the fact recent research from the Office for National Statistics has revealed during the last quarter of the recession, both unemployment and the number of people finding themselves underemployed rose.
TUC general secretary Brendan Barber said: "There is no direct link between excess overtime and underemployment but those people who are struggling to find enough or indeed any hours to work must be wondering why some workers are doing so much for free."
