The player: How Paul Stretford has changed football for ever

It ended in reconciliation rather than a split. The pre-nups were signed and Fergie and Wayne, the happy couple, were a picture of smiles and bonhomie, standing side by side, arms clasped round each other in cordial embrace.

The clinch marked the culmination of a baroque week of rumour, speculation, public claims and counterclaims as contract negotiations between England's most gifted football player, Britain's most successful manager and one of the world's greatest clubs burst out of the boardroom and into the public domain.

At its peak, the convulsions and controversy prompted mass protests and death threats as Manchester and the football-following parts of the nation held their breath in anticipation of the transfer of a player across a bitter divide – from the red side of the city to the blue side.

It also symbolised a dramatic and unmistakable power shift, not simply from United to City, but from club to player, or, more pertinently, from club to player's representative. Paul Stretford, Rooney's agent, did not feature in any of the public relation exercises after his client's new lucrative five-year deal was signed. For many, he was the spectre at the feast. Stretford, a 52-year-old former vacuum salesman, has been blamed for the resulting strife.

Not that Stretford is likely to be hiding away licking his wounds. If reports that he has secured a wage increase for the 24-year-old Rooney – whose salary is now put at anywhere between £180,000 and £250,000 a week – are correct, then it is more conceivable that he is somewhere licking his thumb and forefinger in readiness for counting his own sizeable cut of the deal. The deal has comfortably set a new financial benchmark in the frenzied economic bubble that is English Premier League football. That mark is one he has held previously. The £1m fee, rising to £1.5m if Rooney stayed for five years, that Stretford reportedly received for arranging Rooney's transfer from his boyhood club, Everton, to Manchester United in 2004 is said to have been the highest fee paid to a British agent.

The role of football agents generally, and Paul Stretford specifically, is mired in contention. Broadly speaking, their job is to look after almost every aspect of their client's career, allowing them to concentrate on playing football. They handle employment and endorsement deals, as well as public relations, and generally help them to promote themselves as a product and make money. In return, they take a cut from their clients' wages. This can be anything from 5 per cent upwards, with charitable exceptions meant to be made for young players' wages. When Stretford first signed Wayne Rooney, aged 18, documents show he was taking 20 per cent. In other deals he has been dubbed "Mr 40 Per Cent".

Research by Birkbeck College's Football Unit shows agents have been part of football since its foundations in 1885, being deployed largely by clubs to scout for talent. Their use by players grew in the 1960s and '70s. The former England striker Jimmy Greaves was one of the first to use one when he was at Chelsea in the 1950s. Greaves says their role was very different then. Stan Thomlin never represented Greaves in contract negotiations because no club would countenance an agent's involvement. Thomlin, he says, dealt with "peripheral earners" where a "few bob" could be earned outside the game off the player's name. Thomlin arranged for Greaves to appear on Bovril adverts. "Stan made a few bob and I did. It wasn't a fortune but any extra money a player could make in the era of the maximum wage was most welcome," Greaves said.

The role of agents exploded in the 1990s with the financial growth of the game fuelled by television money. The result has been to turn the game's labour relations upside-down. Clubs originally controlled players' lives through their monopoly of the transfer market and playing contracts. The gradual erosion of that power via the 1961 abolition of the maximum wage, the George Eastham case in 1963 and culminating in the 1995 Bosman ruling, which gives players freedom to move at the end of their contracts, wrenched control away from clubs and handed it to players. They, in turn, have handed it to their advisers – agents.

The explosion in wages and the strong negotiating position players now enjoy has seen the numbers of agents rise dramatically. There are 431 registered with the English Football Association – only Spain has more, at 585. The sports academic Dr Jonathan Magee has written: "The evolution of the modern-day footballer into a high-earning superstar saw the pendulum of power over labour rights shift away from the clubs/authorities and rest with the player and the agent. It is arguable that the agent has become the most important figure in the football market, and more have become involved in the English football business, fuelled by large commission fees available for negotiating contracts that could be worth millions of pounds."

Stretford's deal for Rooney at Manchester United marks the surrender of the one of the last citadels. The power agents now enjoy rankles with chairmen, managers and officials. The former England manager Graham Taylor once bluntly stated they should "all be lined up against a wall and shot". The fees generated from transfers, in particular, result in agents facing accusations of fuelling their own and players' greed, destabilising clubs and exploiting fans. Graham Kelly, the FA's former general secretary, has said agents enjoy a "licence to print money". The role of some agents in a number of cases of corruption has undermined good governance of the sport and ruined its reputation, according to their critics.

For many, Paul Stretford epitomises all that is good and bad about the modern agent. After spotting football's business potential in the 1980s, he began his career as an agent with one client – the Irish Republic striker Frank Stapleton – from his basement. His first deal took Stapleton from the French club Le Havre to Blackburn Rovers. Other clients quickly followed.

Stretford's introduction to Old Trafford came via the former England striker Andy Cole. Cole's big-money switch from Newcastle to Manchester resulted in an increasingly lucrative connection with the champions. Last week Cole recalled his deal with Stretford. "He told me if I signed with him I would never have to work again after football. He told me to sign for a year, and that if I didn't like it then I could walk away. He told me that he was absolutely dedicated to his players. I signed."

It led to Stretford securing responsibility for organising the players' pool for the 1996 FA Cup final. He became a players' pool expert, landing a deal with the Scotland Euro '96 squad. The move was controversial but welcomed by the players who were well rewarded by his efforts. Stretford's enthusiasm to raise money for his clients provokes criticism and there have been widespread complaints about exorbitant charges for interviews and public appearances.

Stretford's involvement with Rooney has been consistently rewarding for both men but has also landed them in difficulties. Stretford first became involved when Rooney's parents, Wayne Snr and Jeanette, decided they wanted him to go to a bigger agency. His existing agent was Peter McIntosh. The deal quickly became messy and murky.

A Merseyside boxing promoter, John Hyland, tried to convince the Rooney family to stay with McIntosh. Hyland and Stretford met, and at one of the meetings Stretford allegedly offered Hyland £250,000 cash as a pay-off. Stretford denies the allegation. Stretford, believing he was being blackmailed, went to the police.

Warrington Crown Court later heard how Stretford turned to the Liverpool and Scottish star Kenny Dalglish to help to broker a deal. The court heard Dalglish arrived at one meeting in a London hotel with a notorious London gangster, Tommy Adams.

The dispute came to a head at a Warrington hotel in June 2003. Stretford secretly recorded the meeting at which he was ordered by Hyland and two other men to sign a contract handing over 50 per cent of Rooney's earnings to them. He refused.

During the trial, Stretford denied poaching Rooney from McIntosh. The deal was initially for image rights alone – for which Stretford took a 20 per cent commission in July 2002. He claimed he then waited until Rooney's contract with McIntosh expired in December that year before acting for him completely. Later it emerged that Stretford's July 2002 contract stated he would represent Rooney fully as a player for eight years – a breach of the rule that players can be signed for a maximum of two. They even signed a further representation agreement in September 2002 – three months before Rooney's existing contract with McIntosh expired and in contravention of the rules. These revelations caused the collapse of the trial as prosecutors admitted they were no longer able to rely on Stretford as their key witness. The three defendants, including Hyland, were acquitted of demanding money with menaces. The Crown Prosecution Service later decided against prosecuting Stretford for perjury.

The trial's outcome forced the FA to act. Disciplinary action was taken against Stretford and he was suspended for nine months and fined £300,000. He returned from suspension in February this year.

Critics claim his handling of the latest Rooney episode may have paid off in the short term but has caused long-term damage to his client's brand value, which was already suffering from Rooney's sexual peccadilloes. Rooney and Stretford stand accused of disloyalty and greed. Rivals describe Stretford as being "thick skinned" and totally focused on the end product – money. Some suggest he is already planning an exit strategy for Rooney that could see a transfer to a club in the US or on the Continent.

For others less involved in the bragging rights of Manchester football, it is the clearest evidence yet that the beautiful game has long since ceased to be a game but is now a business driven by money and greed.