EXAM writers at the University of Cambridge are launching a compensation claim after being forced to sign new contracts with lower pay.

The 12-strong group works for Cambridge University Press & Assessment (CUP&A), a leading academic publishing house that is part of the university.

Today, the Society of Authors (SoA) trade union said that their historic contracts had incorrectly failed to categorised them as workers, so they had been denied rights such as fair holiday pay for up to three decades.

Their claim was only lodged after the workers were told that they would receive no further commissions from CUP&A unless they signed new contracts that would begin formally treating them as workers in April.

All of them signed in May, with the contracts giving them the minimum legal holiday pay rate of 12.07 per cent.

But with the hourly rate for at least some of their work being reduced, this resulted in an overall loss for some workers, said SoA.

The union has instructed law firm Leigh Day to pursue the claim, arguing that the changes made by CUP&A were unfair because the writers had always been entitled to holiday pay, as they should have been categorised as workers.

Human rights solicitor Ryan Bradshaw said: “The adjustments made by CUP&A under the guise of belatedly complying with their legal obligations were, in reality, a thinly veiled pay cut.”

SoA deputy chief executive Sarah Burton said: “Our members are longstanding and committed exam writers for CUP&A and to effectively compel them to sign new contracts which obliged them to take what amounts to a pay cut is shocking and unfair.”

The university was contacted for comment.