The riddle of Rio: why did it take 44 hours for Britain's costliest footballer to take a drugs test?

The unassuming road which weaves between the industrial plants and lorry parks towards Manchester United's training ground at Carrington is regularly plied by vast BMWs and flashy Aston Martins belonging to some of the highest-paid sportsmen in world football.

The car that carried the two officials from UK Sport and an FA representative to Carrington on Tuesday 23 September was an altogether more modest vehicle, but it began a chain of events that led to the most expensive footballer in the country, whose combined transfer value is £48m, exiled from England's most important international since the World Cup quarter-final with Brazil.

The UK Sport officials were "independent sampling officers" whose task it was to collect urine tests from four Manchester United players, chosen at random once they arrived. The FA officer was a doctor, there to ensure that each player complied with the test and the paperwork was in order.

In contrast to football in Germany, Italy and Spain, no Premiership player has been convicted of offences involving performance-enhancing drugs. United believe that the FA, under a new chief executive, Mark Palios, was determined to make an example of a high-profile footballer. Rio Ferdinand is certainly that.

The 24-year-old defender, who cost Manchester United £30m when sold from Leeds in the summer of 2002, is described by colleagues as "a forgetful sort of bloke" and was in the process of moving house to the belt of vast footballers' mansions around Alderley Edge and Wilmslow in Cheshire. Some reports suggest removals vans were sighted at his home.

Ferdinand was training with the United squad when the inspectors called, and was told afterwards that he would be one of the four required to give a urine sample.

The UK Sport sampling officers divide their tests between those carried out during matches and those at training grounds. Players selected at half-time to undergo a test are accompanied by officials until they produce a urine sample once the game is over. Given the physical exertion of a match and the accompanying loss of fluid, some internationals, such as Stuart Pearce and Alan Shearer, have had to stand in a room for more than an hour before they are able to produce a sample.

At Carrington, there was no such requirement. Ferdinand and the three others were allowed to either give the sample once they had finished training or wait until they had showered and changed. Ferdinand, who at Leeds United was renowned as a conscientious trainer, always the last off the pitch, opted to have a shower and then simply left, passing through the gaggle of United fans at the main gate as he made his way to the Harvey Nichols store in Manchester.

The UK Sport officials waited an hour for Ferdinand to emerge, and when told he had left members of United's staff attempted to bring him back to Carrington. Ferdinand, who had missed England's previous two internationals because he was being treated for a kidney complaint, is not apparently a man to answer his mobile phone, and when this failed, he was sent a text message. His response was apparently to exclaim: "Oh my God! I'll come back straight away."

By the time he returned, the UK Sport officials had gone. There is no requirement for them to stay, and it is up to the player to give a test within an hour of being asked to do so.

In athletics, there is a distinction made between refusing to give a sample when confronted by officials and failing to keep an appointment, although that will disappear next year. The FA does not make that distinction, and by driving away Ferdinand was in breach of rule E26, which carries a maximum two-year suspension.

United insiders say the doping control officers were unable to return to Carrington immediately and that the earliest they could come back was on the morning of Thursday 25 September. Ferdinand underwent the test, which proved negative, 44 hours after the original was due to have been conducted. Only then would Ferdinand have been made aware of the seriousness of his position.

The England coach, Sven Goran Eriksson, knew of the happenings at Carrington as early as 10 days ago and had two conversations with the Manchester United manager, Sir Alex Ferguson, before the news broke.

It is speculation, but the pressure might well have contributed to Ferdinand's remarkably below-par display against Stuttgart last Wednesday, where he was at fault for both German goals and gave away a further penalty with a dreadful, schoolboyish tackle on Kevin Kuranyi, a striker he never came close to mastering. Ferguson, who in contrast to his dressing-room performances rarely criticises his players in public, labelled his display and that of others in the Manchester United defence as "terrible" and "sloppy".

Two days afterwards, as United returned to Carrington for their first full training session after the Champions' League defeat in Germany, Ferdinand received a letter from the FA, stating he had failed to attend a drugs test.

On Saturday, when Ferdinand played Birmingham City at Old Trafford, the Manchester United chief executive, David Gill, was told the player had not complied with drug-testing regulations and risked being dropped from the England squad to play Turkey.

The FA insisted the decision to omit Ferdinand was taken only yesterday morning, after what one source said was "many, many hours of debate and discussion, looking at things from Rio's point of view". Mr Eriksson was informed of the FA's verdict and accepted it.

The reaction from Old Trafford was one you might expect from the biggest club in the world. Since the weekend, Mr Gill had been taking legal advice in an attempt to overturn any FA ban, while the chief executive of the Professional Footballers' Association, Gordon Taylor, alleged that the club threatened to pull out all four of its remaining players from the England squad.

The FA claims that although its executive director, David Davies, explained the starkness of his situation to the player on Sunday morning and met representatives from United in the afternoon, neither the club nor Ferdinand made themselves available when the FA requested a formal interview on Monday. Mr Palios and Mr Gill did speak on Sunday evening, but United claim the FA chief executive then refused to take their calls. Mr Palios's point of view was that he would speak with Mr Gill but not his lawyers.

Another attempt to convene a meeting also foundered but by then the club had a letter from the FA telling them their most expensive asset must attend a hearing next Monday.