Attention all lawyers who believe in the pursuit of maximum profit.

The newly merged firm of Thompsons is not for you.

It could seriously damage your income.As evidence, the Thompsons partnership deed states: 'The principal object of the partnership shall be to assist trade unions and their members.

It shall not be the object of the partnership to earn for the partners the maximum income which in general practice they are capable of earning.'To this end, Thompsons -- as of 1 May 1996 the largest trade union and personal injury firm in the country -- never acts for corporate employers or insurance companies.

This policy does have an impact on the bottom line, admits partner Tom Jones.

'There's no doubt that we could have earned more by taking up other sources of wo rk and that people working here could go off and work at a defendant firm and earn more money.

But that's not what we're here for and it never has been,' he explains.The add-on services the firm provides to its trade union clients are a further drain on resources.

These include fixed-fee conveyancing at £285 and double will writing at £52.50, as well as a free legal advice service for union members.But it is not just philanthropy.

Trade unions are shrinking and so competition for their legal work is increasing.

'We stake our ground and make it very clear which side we're coming from,' explains Mr Jones.'We're saying: why go to a firm that will act for both sides when you can come to a firm that acts for only one side and commits itself to trade unions?'The merger brought back together a firm that split in 1974.

According to David Thompson, the founder's grandson, the driving forces behind the reunification were the dual factors of competition and the need to be bigger to offer a better service: 'Changes in the PI market had put pressure on both firms.

The system means you have to work harder to earn less, and the two firms were more in competition with each other.'The vast majority of the firm's work is in the personal injury field, where it has won a number of test cases and campaigns strongly for change.

'Our experience is that the English legal system is largely unsympathetic to working people and is stuck in the past,' says Mr Jones.

He maintains that compensation levels should rise -- describing current levels as 'pathetic' -- and that the burden of proof should be reversed.

'It is obscene for an individual to have to prove whose fault it was,' argues Mr Jones, who favours no-fault compensation.PI partner Keith Taylor explains: 'Our average client is a working trade union member who finds it difficult to accept that he can go to work, get injured in the course of his duties, possibly to the extent that he cannot work again, and that then he should have to mount a case as to why he should be compensated.'The firm's other main area is trade union work, which has previously seen it offering 24-hour support to the miners' strike and the Wapping action.The firm is literally at the centre of the trade union world, sharing Congress House with the Trade Union Congress.

Stephen Cavalier, head of the employment rights unit, says that trade unions have learned over the years to use employer-friendly legislation to their own advantage.'Unions have recognised that they have to use the law as part of their industrial armoury,' he says.

'The selective deployment of strategic legal cases is part of providing a service to members.'The firm's openly left-wing stance is a major selling point to potential staff and Mr Jones says the firm has a low turnover of lawyers.

'All partners are sympathetic to the trade union movement,' he says.

'You wouldn't work for Thompsons if you weren't.' Mr Cavalier agrees.

'It's enjoyable to do something you believe in.

Perhaps not every lawyer can say that, but it's certainly one of the things that drives us forward.'HISTORY OF A TRADE UNION LAW FIRM-- 1921: founded by WH Thompson, who was imprisoned as a conscientious objector during the First World War.

His wife was a suffragette.-- 1921: first major case was acting for imprisoned councillors during the Poplar rate strike, which led the government to change its rates policy towards poorer London boroughs.-- 1947: WH Thompson died, leaving a firm with 70 staff.

Taken over by son Robin, with other son Brian joining soon after.-- 1974: Brian and Robin set up separate, but linked, firms.-- 1994: Robin stepped down.-- 1995: Brian stepped down.-- 1 May 1996: the firms merged to form Thompsons.

Brian and Robin act as consultants.

Robin's son, David, chairs the firm's policy group.KEY FACTS-- The new firm has 89 partners and, in total, over 800 legal staff in 13 offices in England and two in Scotland.-- All staff are trade union members.-- It is now the largest personal injury and trade union firm in the country.

It only acts for individuals and their trade unions.-- The firm recovers an average of over £100 million in compensation every year.-- It won the highest ever damages settlement -- £3.4 million for a client catastrophically injured in a car crash.-- The firm has won test cases in asbestosis, deafness, stress injury, passive smoking, employment rights and equal rights.