The union is alleging that outsourced workers at the University of London are being denied their rights under article 11 of the European Convention on Human Rights (ECHR) because they can only negotiate their pay and conditions with the outsourcing agency, not the university directly.

The case carries significant implications for the UK’s 3.3 million outsourced workers.

The Department for Business, Energy and Industrial Strategy (BEIS) is intervening in the case in support of the university.

According to the IWGB, the use of “middlemen” in the form of outsourcing companies is allowing employers to offer some workers far worse pay, holiday entitlements, sick pay and pension contributions than those they directly employ.

Jason Moyer-Lee, general secretary of the IWGB, told Left Foot Forward: “For decades employers have used outsourcing as a way of evading their responsibilities towards the people who provide labour for their businesses.

“This is true in terms of pay, terms and conditions, as well as collective bargaining. With arguments based on the European Convention of Human Rights, this case calls for a course correction.

“If an employer calls the shots on workers’ pay, terms and conditions, then they should have to negotiate with the workers’ union.”