In a letter to Theresa May on 19 June, Mike Clancy, the union’s general secretary, said the Treasury’s pay guidance for civil service departments and agencies was “not fit for purpose and needs to be revised to reflect the will of the electorate and the needs of the workforce”.

He also called for “a truly independent and evidence-led review of pay and reward for the civil service and the wider public sector”.

Clancy pointed out that, since 2010, many of Prospect’s 28,000 professionals, managers and specialists in the civil service and the wider public sector have seen their pay fall by more than 15% in real terms.

“Unlike other public servants many have also seen the removal of ‘progression’ pay, which has compounded the position,” Clancy added.

He said pay and benefits in the civil service and the wider public sector now lag significantly behind those available for comparable jobs in the private sector and the gap is forecast to widen.

“Employment in the civil service and the wider public sector is becoming increasingly synonymous with low pay, long hours and unmanageable workloads,” said Clancy.

“The problem has been compounded by dramatic headcount reductions. The civil service has reduced in size by about 26% in recent years, leading many commentators to question the capacity of the civil service and our wider public services to deliver on Brexit and broader aspects of government policy,” he added.

He said it had never been more important to ensure that the civil service, and the public sector more widely, is able to recruit, retain and motivate the skilled staff it needs.

“We believe the general election sent a clear message that the electorate wants a government which invests in public services and treats public servants fairly by ending the 1% cap on their pay,” he said.

Clancy concluded by calling for an early meeting with Damian Green, the new Cabinet Office minister.