The 40th anniversary of the Government Communications Headquarters’ trade union ban will be marked next week as hundreds are expected to march in Cheltenham.

The joint Public and Commercial Services (PCS) union and Trade Union Congress (TUC) event is planned for Montpellier Gardens at noon on January 27 to mark one of the movement’s most important victories.

In 1984 Margaret Thatcher’s Conservative government banned trade unions at GCHQ citing security concerns.

Most workers quit their unions, but fourteen refused as a matter of principle and were sacked.

The campaign to reinstate them was led by PCS’s forebear, the Civil and Public Services Association (CPSA), and saw speakers travel more than 150,000 miles and attend more than 350 events, including annual marches through the town centre, to keep the issue in the public eye.

Their persistence paid off when, in 1997, the newly-elected Labour government lifted the ban and they were able to return to work.

Stroud district councillors Doina Cornell and Trevor Hall from the Community Independent group on the council will be there to help steward the event.

Doina Cornell said: "That this national demo should be right here on our doorstep in Gloucestershire is a call to action for all union members and in fact anyone who is concerned about the government's continuing class war against ordinary working people.

"It's time to get out and let the government know how you feel."

Trevor Hall said: "Never in my lifetime have I seen a government try so hard to undermine the basic rights of honest working people.

"They should be ashamed of themselves for taking it this far and it's time we showed them that we have had enough."

Mark Serwotka, Paul Nowak and UNISON general secretary Christina McAnea have already been confirmed as speakers on the day, with others expected to be added soon.

The surviving members of the original campaign – Alan Rowland, Robin Smith, Brian Johnson and Gareth Morris – and their families will be attending as guests of honour. A pamphlet and commemorative film is also being produced.

The Government and GCHQ declined to comment.