Research by the Trade Union Congress (TUC) finds that more than one in five workers (21 per cent) regularly worked unpaid overtime last year, an increase of 0.7 per cent since 2009 and the highest proportion since 1997.

Last year 5.26 million workers in the UK clocked up an average seven hours 12 minutes unpaid overtime a week, worth £5,485 per person and a record £28.9 billion to the economy.

TUC general secretary Brendan Barber says, ‘With tough economic conditions making employers reluctant to recruit, existing staff are picking up much of the increasing workload through unpaid hours.

‘While most staff are happy to put in some extra free time to help their company through, forcing staff to endlessly put in too many hours could lead to increased stress levels, which can make staff ill and reduce the quality of the work they do.’

See also: Your overtime pay and working rules questions answered