Legal action threatened over bank of invoices and national insurance numbers taken from Midlands address

A blacklist of more than 3,000 construction workers used by several major contractors is understood to have been uncovered, according to union sources.

Ian Kerr, a private consultant, is understood to have had his Worcestershire office raided and computer and files seized by Data Protection Services, over claims they contain the names of 3,200 blacklisted construction workers.

In addition to the workers' names and national insurance numbers, 40 invoices were discoverd from major construction firms who are alleged to have used Kerr's services, reportedly to check up on potential employees.

The blacklist relates back to projects in the M&E sector hit by industrial disputes during the 1990s and early 2000s, including the Jubilee line extension and the Royal Opera House. It is said to contain the names of workers involved in trade union disputes and employment tribunals.

The existence of an M&E blacklist was first uncovered by Building in 2006 after Alan Wainwright, a regional resources manager at a large contractor within the sector, published allegations on the internet.

According to Wainwright, a blacklist of electricians was being circulated among leading M&E firms with the intention of ensuring that they were not employed.

Now, the row has resurfaced with allegations that Kerr, understood to be a retired special branches officer, was in the employ of various large contractors to vet potential workers.

Steve Acheson, a Unite branch official, said he had been approached by the Information Commissioner’s Office, which is leading the investigation, over a year ago.

He said: “We’ve been waiting for this, we knew our human rights were being breached by this list, now hopefully this raid will provide evidence of this.”

If the list of names and invoices are found to be in Kerr's possessions, many firms could face lengthy law suits.

Tony Jones, 42, previously worked on the Jubilee line and believes he is on the blacklist. He said: “The firms should be held accountable - they've been taking food out of children's mouths. That's what it comes down to.”

The Information Commissioner’s Office is an independent authority set up to promote access to official information and protect personal information. A spokesperson for the body said an official statement on the raids would be made tomorrow.