Another legal case is being brought on behalf of workers in the so-called gig economy who say they are being denied their rights.
The GMB union has launched proceedings against delivery company DX on behalf of six workers.
DX drivers are currently viewed as self-employed contractors by DX, meaning they are denied basic rights such as holiday pay and national minimum wage, said the GMB.
National officer Justin Bowden said: "It is high time that gig economy employers like DX stepped up to their responsibilities for those who put in the hours for them.
"GMB will continue to challenge this shameful practice wherever we can.
"Multimillion-pound employers need to realise that they cannot continue to avoid basic workers' rights."