by Steve Schifferes BBC News Online economics reporter

As the TUC conference begins in Blackpool, BBC News Online looks at the history of the trades unions and their political influence.

The Trades Union Congress is the oldest, and at one time the most powerful representative body of working people in the world. Founded in 1868, it co-ordinated the efforts of skilled workers to gain recognition from employers and lobbied the government to give more rights to workers.

The TUC General Council in 1921- when it first met

It took the unions nearly 40 years to ensure the right to strike, and in the process of political lobbying they established a Parliamentary Committee that eventually became the Labour Party.

From the early days of the Labour Party, most MPs were trades unionists, and the unions provided the funds and the local organisation for the party.

From skilled to unskilled

The importance of the unions in the political process was paralleled by the extension of their own membership to the mass of unskilled workers from their original base in skilled workers.

By the l920s, boosted by the industrial struggles of the First World War, the great industrial unions like the Transport and General Workers Union and the General and Municipal Workers were formed.

They led a general strike in 1926 to support the unsuccessful attempt of the coal miners to maintain their wage rates in the face of the slump.

In an uncanny parallel to the present, the Turner-Mond talks of the late l920s - an early attempt to build industrial partnership - were the result of the failure of the industrial militancy of the first quarter of the century.

In another parallel to today, the Labour Party - which formed its first two governments in the 1920s - also sought to distance itself from the unions.

Indeed, the l929 Labour government fell from power when Ramsay MacDonald decided he had to follow the advice of City bankers rather than his trade union allies in the financial crisis brought on by the Wall Street crash.

The pinnacle of power

The Second World War boosted union membership to unprecedented heights - and the co-ordination of industrial production brought the unions to the heart of government - with Transport and General Workers Union leader Ernest Bevin becoming Minister of Labour.

Union leader Ernest Bevin joined Churchill in the War Cabinet

The 1945 Labour government did much to strengthen the role of unions in the political system by attempting - at first successfully - to restrain wages and raise productivity by a series of voluntary deals.

These reforms culminated in a "tripartite" system of consultation between unions, business and government. By the l960s it sometimes seemed that the unions were more powerful than the government in setting economic policy.

Mrs Thatcher and the unions

But by the 1970s the unions were held responsible for some of the industrial decline of the UK economy, and pay policy became untenable in the face of worldwide inflation.

Mrs Thatcher's Conservative government came to power in l979 determined to reduce the power of the trade unions.

Her defeat of the miners in strike in l984, as much as the development of legislation to make strike more difficult, changed the climate of industrial relations permanently.

The number of strikes declined to record lows, as unions sought partnership rather than confrontation in a climate of high unemployment.

"Fairness, not favours"

After the electoral defeats of the l980s, the Labour Party sought to distance itself from the trade union movement.

Mr Blair had new friends rather than the unions

Firstly, by introducing One Member, One Vote it sought to reduce the influence of the union bloc vote at Party Conferences.

Under Tony Blair, the process went further. He pushed through the reform of Clause Four, the Labour Party's commitment to socialism, against union opposition.

And he made it clear that he would not repeal the bulk of Conservative trade union legislation.

"Fairness, not favours," would be Labour's policy towards the unions, Mr Blair proclaimed.

Although Labour in power has implemented its electoral commitments to the minimum wage and union rights to recognition in the workplace, the government - in union eyes - has often seemed more interested in wooing business interests.

A new generation of leaders sought partnership with companies

But many new rights have been won because Labour has adopted the social chapter of EU legislation.

In its second term, Tony Blair has committed his government to reforming the public sector with higher taxes to pay for better services.

But unions fear that reform will mean lower wages and worse conditions for workers in the public sector - who now make up a majority of union members.

And they now fear that the government is rushing into a war against Iraq.

With the strong economy boosting union power, the stage may be set for an historic confrontation.