They claim Sir Robert McAlpine was involved in an unlawful conspiracy to amass a database of information against them, which robbed them of their livelihoods.

The initial claim involves 86 of 3,400 workers in the files of the Consulting Association, the shadowy organisation paid by major contractors to collect damaging information about individuals trade union membership and political views.

The workers are being represented in the High Court by Sir Hugh Tomlinson QC celebrity barrister to the stars in the News of the World phone hacking cases.

The group alleges McAlpine had the worst record of blacklisting, which is why it is being targeted in the legal action.

The conspiracy charge means McAlpine would also be responsible for the actions of more than 40 other contractors that systematically blacklisted workers simply for being members of a trade union.

Many of the workers said they were repeatedly dismissed from major construction projects and in some cases suffered years of unemployment.

The average claim has been estimated at £20,000 bringing the value of the first wave of compensation claims for loss of earnings and damages to around £17m.

Many more of the blacklisting victims are expected to add their names to the action in the coming months, raising the potential total pay-outs building firms could face to more than £600m.

Mick Abbott, 74 year old ex-scaffolder said: “This nearly ruined my marriage and it meant that my children were on free meals at school.

“My file goes back to 1964 and the last entry says that I rekindled the campaign for justice for the Shrewsbury picketers in 2006.

“They have been watching me all these years and passing this information around, blighting my life over four decades.”

Steve Kelly, electrician and spokesperson for the Blacklist Support Group said: “I was blacklisted because I was a union member and because I raised issues about safety.

“Over the years I suffered severe financial strain. The blacklisting firms should be made to pay compensation for years lost and years in future.”

A spokesman for Sir Robert McAlpine said: “As legal proceedings have been issued it would be inappropriate for Sir Robert McAlpine Ltd to make any comment at this stage.”