Labour’s powerful ruling body, the NEC, decided to take the contractor’s passes away after members raised concerns about Carillion, which is facing court cases from workers over alleged blacklisting.

Steve Rotheram MP and Jim Kennedy Ucatt national political officer were among those calling for Carillion to be expelled from next week’s conference.

In order to allow Labour to refund the cash that Carillion had paid for the exhibition space and to ensure that the firm had no role in conference, Ucatt’s executive council agreed to donate £11,000 to the party to cover the loss of revenue.

Steve Murphy, general secretary of Ucatt, said: “I am delighted that the NEC has agreed to bar Carillion from exhibiting at Labour Party Conference.”

Murphy added: “Blacklisting is a nasty, vicious and secretive practice. Until those responsible both apologise and pay compensation to their victims they should be barred from the democratic process.”