Recent research by the Resolution Foundation think-tank suggests that more than a million workers in Britain do not receive any of the holiday pay they are guaranteed by law.
The report says as many as one in 20 workers did not receive any holiday pay despite being entitled to at least 28 days a year.
It also found that some workers are unable to calculate whether they are receiving the right level of pay as almost one in 10 do not get a payslip. HMRC has identified 200,000 cases of workers not receiving the minimum wage.