£7.3 billion worth of unpaid overtime work, more than the next two regions - the South East and the East of England - combined.
These employees performing an average of 8.4 extra hours per week, also the highest in the UK,
The average loss per employee was £10,796.
Unpaid overtime was more common in the public sector, where 14.8% of employees reported working extra hours without pay, compared to 11.7% in the private sector.
“Nobody minds putting in longer hours for time to time,” TUC Regional Secretary Sam Gurney said. “But some workers in London put in thousands of pounds worth of unpaid overtime last year. Unpaid hours should never be a regular habit – that’s just exploitation. With staff shortages in many industries, work intensity and pressure to work longer days is a big problem.”