Protesters from the Blacklist Support Group turned-up outside the Grosvenor House Hotel in London’s Park Lane where guests were arriving for the Building magazine awards

The group attempted to present its own awards including a “Blacklister of the Year” trophy to contractors attending the event.

The demonstration is part of an ongoing campaign following the prosecution last year of the Consulting Association – a body which for decades had been covertly compiling a database of building workers who raised concerns about unsafe conditions or complained about non-payment of wages.

The blacklist was used by building firms to dismiss workers or deny them employment on major projects.

A spokesman for the group said: “Blacklists do not compile themselves. It takes senior managers to collect, collate and pass on the information. Some of the very same people and companies will be collecting awards at this ceremony tonight.”