Trade union activists across Britain warned David Cameron and his worker-bashing corporate backers yesterday that they will have no peace until blacklisting is wiped out.

Demonstrations and lobbies marked a TUC-backed day of action to demand a powerful public inquiry into the vicious practice which ruins lives, plus full compensation for thousands of victims.

In Leeds a peaceful demonstration outside a shopping centre where leading blacklisting company Robert McAlpine has an office led to a protester being hospitalised by heavy-handed security.

Outside Parliament TUC general secretary Francis O'Grady contemptuously dismissed Mr Cameron's sham tactic of attaching the issue of blacklisting to his dangerous stunt of launching an inquiry into trade union practices.

"Blacklisting is too serious an issue to be tacked onto the government inquiry set up purely to devise laws to limit union campaigning," she said.

Ms O'Grady noted that the barrister chairman of the inquiry Bruce Carr was well-known for acting on behalf of employers.

"Now he is going to investigate whether or not trade unionists are allowed to protest in posh neighbourhoods or outside yacht clubs, or whether carrying a giant mouse is a criminal offence."

Unite general secretary Len McCluskey said the government's inquiry into unions should be redirected at the cartel of 44 employers which colluded over decades to blacklist and destroy the lives of working people.

Meanwhile Unite assistant general secretary Gail Cartmail announced a major new legal offensive in the High Court on behalf of blacklisted workers.

Addressing campaigners who swooped on Westminster to lobby their MPs, Ms Cartmail condemned the Information Commissioner's Office (ICO) for taking years to contact some of the 3,213 people who were known to be on the infamous Consulting Association blacklist.

The ICO belatedly confirmed yesterday that a further 1,200 victims will get a letter in the next few days telling them that they were on the blacklist.

Construction union Ucatt general secretary Steve Murphy also announced that his union was starting new legal proceedings.

Referring to the offer by some bosses of a limited compensation scheme, GMB general secretary Paul Kenny declared contemptously that "a few pounds" would not "buy-off the bloodstains" of the victims.

"Throwing a few quid on the table is not the answer here," he said. "We need that public inquiry and justice."

Blacklisted workers Bill Parry, Dirk McPherson and Steve Acheson received thunderous applause as they pledged to keep on fighting for justice at the Westminster lobby.

Blacklist Support Group co-ordinator Dave Smith also delivered a rousing speech condemning the "human rights conspiracy" unleashed by multinational companies and the state, with the involvement of every section of the Special Branch across the country.

Labour leader Ed Miliband sent a message of support to the anti-blacklisting protesters, demanding a full-scale inquiry.

The peaceful demonstration in Leeds turned ugly when protesters Pete Shaw and Sandy MacPherson were set upon by security guards at the city's Merrion Centre as they tried to access facilities there.

They were manhandled and flung through the doors onto the floor outside, leaving Mr Shaw in need of cardiac care.