The man, who lives in Scotland and is now in his 70s, has said he wants to accept the money, even though his union believes he is entitled to over £320,000 because of the way his career was affected.

Offers have been made to 11 workers whose names were on the blacklist, which came to light in 2009 during a raid on the Consulting Association by the Information Commissioner’s Office.

Offers range from £10,000 to £60,000 and total £415,000, according to solicitor Leigh Day, which is involved in the case.

A total of 3200 construction workers and environmental activists were named on the blacklist and used by dozens of building companies to vet new recruits. Many of those on the list say they were regularly rejected for jobs, leading some to leave the country to look for work.

A compensation scheme has been launched by construction firms, but unions are pressing ahead with legal action, with a High Court hearing due to be held next May.

The GMB union said offers to the 11 were “derisory” and added only around half those on the blacklist know their names were included.

Legal officer Maria Ludkin told the Guardian: “It is an indication that the defendants are worried about going to trial. We are looking forward to seeing them in court. The total value of our claim is £30m and we will be fighting for every penny.”

Further details of what was written about those on the blacklist were also revealed on Tuesday, showing how information was sent to firms when people applied for a job.

One worker was described as a “strike leader” after he applied for building work on a hospital, with the entry: “Main contact given details. Company has not employed.”

Another entry read: “Was shop steward, involved in safety issues.”