Fredrick Engels once defined the state as "armed bodies of men", together with their appendages, in defence of private property. Last month's BBC 2 TV programme entitled True Spies by Peter Taylor examined one of these appendages, Britain's secret services.

The programme revealed how in "democratic" Britain, MI5 and the Special Branch systematically infiltrated political groups and organisations, and secretly spied on trade union leaders such as Arthur Scargill and Derek 'Red Robbo' Robinson. While none of the revelations are particularly startling, what was of interest was the use of first-hand interviews by ex-M15 agents in explaining their sordid undercover activities.

Of course, the activities of the Secret Services are nothing new. According to Peter Wright, M15's most famous director, agents "bugged and burgled [their] way across London at the state's behest." The ruling class uses these agents to spy on and disrupt so-called "subversive" organisations that are regarded as a threat to their system.

More than two hundred years ago, at the dawn of the British trade union movement, the government employed spies and agent provocateurs to infiltrate and undermine the workers' organisations. Their reports led to the imprisonment, deportation and even hanging of trade unionists. Originally this spying agency was part of the Metropolitan Police. However, in 1916, the Secret Service Bureau was relaunched as part of the Directorate of Military Intelligence and renamed MI5.

After the First World War, it developed its network of agents to monitor "subversive" organisations, in particular the Communist Party. Later, this was broadened to include such organisations as CND and Liberty. In the 1960s, the Police Act introduced regional Special Branches, and by 1975 every provincial force had its own full-time Special Branch in operation.

In the early 1970s, the Special Branch set out to closely monitor the growing industrial unrest that was sweeping the country. Within a few weeks of the 1972 miners' strike MI5 shifted its emphasis to "domestic subversion", particularly the "far and wide left". MI5's F branch acted as an anti-subversion section monitoring the trade union field and rapidly expanded.

MI5 even had the leader of the Labour Party, Harold Wilson, under surveillance in the run up to the 1974 election. MI5 had a file on Wilson codenamed "Henry Worthington". Though officially denied by MI5, the author of 'Spycatcher', Peter Wright claims he and "a few malcontents" within MI5 conspired to bring down the Wilson Labour government.

However, this didn't prevent Wilson using M15 bugging transcripts and informers' evidence to denounce Communist influence in the 1966 seamen's strike. At that time, one National Union of Seamen committee reportedly consisted entirely of Special Branch informers, and the union's right wing officials were regularly informed about the activities of union militants. In his second term as Prime Minister burglaries were carried out against Harold Wilson and his senior staff by MI5.

The "secret state", which has no accountability to Members of Parliament, is regarded as a vital weapon by the Establishment in its underground activities against all those who pose a threat to capitalism. The trade unions and leftwing organisations and specific individuals were marked out for special attention. Key right wing union leaders were identified by M15 as possible recruits or informers. The BBC investigation revealed that Joe Gormley, former president of the National Union of Miners, was a Special Branch informant during the 1970s.

In True Spies a former Special Branch officer claims that Mr Gormley passed on details of Arthur Scargill's and other miners' plans for industrial action in the early 1970s. But, despite receiving warnings from the top of the union, MI5 and the government failed to head off the 1972 strike. In fact, the Special Branch officer - referred to only as Alan - claims that MI5 told the government the strike would not happen, with devastating consequences for the leadership of the day.

Edward Heath's government was toppled in 1974, following mass industrial action, in what became known as the "Who Runs The Country?" election.

The M15 agent told the programme: "The extreme left were getting the upper hand and were dictating the policy of the unions to some great extent, then we found ourselves actually going to unions and talking to the top union officials about what was going on.

"One of them would be Joe Gormley... certainly he was in a position of power and was in a position to furnish us with what we were looking for." He added that Gormley turned informer because "he loved his country. He was a patriot and he was very wary and worried about the growth of militancy within his own union".

Arthur Scargill himself was not surprised by Gormley's "patriotic" actions, saying: "The history of our movement is littered with people in leadership positions who were either connected with the Special Branch or connected with the State."

Joe Gormley, who died in 1993 and was president of the NUM until 1982, was not the only trade union leader to have links with the "secret state". True Spies reporter Peter Taylor discovered that Special Branch was talking to more than 20 senior trade union leaders during the early 1970s. Again, this revelation did not shock Scargill, who said correctly he was only surprised that there were not even more spies within the unions.

Another Special Branch officer claims that Ford, which had a giant car manufacturing plant at Halewood on Merseyside, only agreed to invest there because of a suspected secret deal with MI5 and Special Branch.

According to Former Special Branch officer, Tony Robinson, the entire workforce was routinely vetted. He said: "My senior officer said: 'One of your responsibilities, Tony, is to make certain that the Ford factory is kept clean of subversives.'

"And part of the plan drawn up was to make certain that work would carry on smoothly at Ford without the expected Merseyside disease of strikes and layoffs."

He told the programme that every week Ford would secretly submit a list of the latest job applicants to the local Special Branch. "We were expected to check these lists against our known subversives, and if any were seen on the list then strike a line through it," he said.

He added: "It was very, very important that the unions were monitored, and I, as a Special Branch officer, make no apologies for doing it as efficiently as I could. We're talking about thousands and thousands of families dependent on continued employment... you have a small group of subversives who can bring that factory to a stop, then I think the ends justify the means."

The programme interviewed Tom, a former trade union activist and Communist Party member, who was secretly vetted by Special Branch and denied a job at Ford's Halewood plant. Obviously very bitter he said: "How can you be proud of Britain when there's things like that going on?"

A Ford spokesman said: "We cannot confirm that Police Special Branch officers were involved in any way in the checking of job applicants or the alleged agreement with MI5." In any case, the vetted workforce did not prevent the Ford plan becoming militant. This was down not to "subversives", which is typical of the police mind, but the conditions imposed by Ford management.

In the 1970s Derek Robinson was the union convenor at the British Leyland plant at Longbridge, at the time Britain's largest factory. He was eventually victimised and sacked. The programme showed how managing director Sir Michael Edwards conspired with the government and M15 to get rid of Robinson. Phones and meetings were bugged by the secret services and the transcripts were shown to Edwards, who used them to plot Robinson's downfall.

Special Branch Officer Tony Robinson, summing up his work, said: "I suppose the whole business of being a Special Branch Officer in many instances is based on lies, on deception or you can't do your job."

Today, despite the official pronouncements to the contrary, M15 continues to monitor "subversive" organisations and individuals on the left. This 2,000-strong domestic spying outfit is now housed in The Thames House on Millbank, especially converted for a trifling £238 million. Its resources have been switched from unmasking Soviet agents to the work of "counter-subversion" and "counter-terrorism".

In a public relations exercise, M15 was introduced into the public gaze, with Stella Rimington, M15's first woman director-general, (known affectionately as 'Mrs R'), even appearing on television speaking about the virtues of modern spying. She appears in the True Spies programme, and in the manner and tone of her interview, shows her utter contempt for so-called "subversive" leftwing ideas and groups, which she regards in effect as the "enemies within." Despite her air of reasonableness, she is, as are all the tops of the secret services, reactionary through and through.

Rimington made her name - the veritable Queen of Spies - within the "service" in the state's secret war against the miners in 1984/85. She was head of F2 section, which targets trade unions and industrial disputes, and an M15 assistant director, which gave her overall control throughout the year-long miners' strike. Admired by Margaret Thatcher, the secret services in conjunction with the other arms of the state, were used to undermine the strike and discredit the leadership of the NUM. While this is not the main reason for the defeat of the miners' strike, it clearly shows the lengths to which the ruling class will go to defend its interests.

While many in the programme said they were "shocked" by the M15 activities, Scargill took a more sober view. "I am not shocked. I am in opposition to capitalism. I am for socialism. For the establishment I am a subversive and will be, of course, subjected to this surveillance."

Again, the state is made up of armed bodies of men in defence of private property. For those fighting to change society, it is clear that they will be subject not only to surveillance, but all the dirty tricks that the ruling class can muster to maintain their power and privileges. We have to expose their role, including that of the CIA, and their subversive activities within the labour movement, and warn against the dangers they pose to democratic rights.

It is the duty of the trade unions to set up a monitoring group to investigate and expose the interference of the intelligent services within the labour movement, especially the covert activities of rightwing organisations and publications. And we should demand the disbandment of M15, M16, the Special Branch, Military Intelligence and other secret intelligence sections. In addition, the files kept by the Secret Services on millions of people should be destroyed.