Manchester United's magnificent skills factory, nestling in the suburbs of the city, stands as a monument to the club's long-held commitment to youth development.

On entering, young aspirants gaze up at huge photographs of graduates from the famous 1992 FA Youth Cup-winning side such as David Beckham, Gary and Phil Neville, Paul Scholes and Nicky Butt.

They have become the poster boys for the club's pioneering approach to the production of young talent, their subsequent achievements also delivering a glorious rebuttal to Alan Hansen's assertion that "You can't win anything with kids". Yet 15 years have passed since that precocious pack began to emerge. Indeed, some of the current academy acolytes were not even born in 1992.

There is another sense in which Beckham et al have become anachronisms, products of a bygone era in which the club were able to set their own agenda in youth development. They may continue to invest huge sums of money and time to the cause, but United have found their pace-setting endeavours hamstrung by an academy system which they perceive as having fundamental flaws.

Serious questions have started to be asked about the system in recent months, not just by United, as the expected new generation of technically accomplished homegrown players have failed to emerge. Howard Wilkinson, the former technical director of the FA, claimed that the system would yield a World-Cup winning side within a decade. That was eight years ago and tumbleweed now rolls across the training pitches which were supposed to be populated by world-class talent.

Brian McClair, the former Celtic and United striker, took over as United's academy director last summer and, in conversation at the club's Carrington training ground recently, conveyed a deep dismay at the inherent problems in the system. In particular, he highlighted the geographical restrictions which have been placed on the pursuit of excellence. "We can only recruit boys up to the age of 14 from a 60-minute travelling distance radius of Manchester," he says. "In that area there are lots and lots of academies and centres of excellence chasing the same boys. It's very competitive."

However, it is the contractual agreements youngsters enter into with academies which McClair believes is an even bigger problem. "The boys all want to be involved in the academy systems, so what happens is that they sign up at eight years of age and you never see them again. You're not allowed to scout any other academies. A lot of parents don't understand that as soon their kids come into the academy system they are right away entering into a compensation system where there are no rules.

"You're asking boys and their parents to make career-defining decisions at the age of eight. That can't be right. Sometimes we can't tell all the way through to 17 and 18 now how good youngsters are going to be because their performances go up and down so much. You have no chance at eight. It's a 10-year programme.

"People want to try and keep their best kids, but it might not be the best for a kid to be involved in a system where he's not able to practice with the best players. Players improve by playing with players of equal or more ability.

"If a boy is in a system which won't let him flourish because the players he's playing with and against aren't challenging him, then eventually he will fall by the wayside. The problem is that if a boy gets released from an academy then they don't then go back into schools or boys football, they stop playing altogether. So you're not going to pick them up again at 12 or 13.

"If you take a 12-year-old boy who wants to come to Manchester United - unless you can agree a compensation fee with the club he's coming from, then you could end up going to a tribunal. There's no rhyme nor reason involved, they just pluck figures. It's a case of they're a big club maybe they can afford it'. To me it's not right boys at that age are having such values put upon them."

McClair identifies a shrinking pool of potential talent, which has its roots in societal change, as another element of the problem. "It's something here that maybe happened in Scotland a bit earlier. Kids are doing other things," he added. "If I had a computer or Sky or DVDs I might not have gone out and played football. Kids don't do enough sport at school either. They are not active enough. It's not just about football. It's about climbing trees, jumping off walls."

United continue to push for structural change in the academy set-up and have strong opinions on the best way to foster technique amongst youngsters. One of their main ambitions is for a switch to smaller-sided games between the ages of eight and 12, the so-called golden age of learning. At the moment, it is eight v eight, but United's theory is smaller games gives young players the opportunity to get more touches on the ball and develop their short passing skills. It is hardly rocket science but they have encountered resistance in their attempts to bring it in. McClair is mystified.

"We've piloted the four against four for numerous reasons, but it's not been adopted universally. We feel that the more contact you get with the actual ball, the better you become. There seems to be such a rush here to get to 11 against 11. It goes to 11 against 11 at under-12s, but why not progress it? Five v five, six v six, seven v seven, all the way up and you could adjust the pitch accordingly . . . Eventually you would get to a place where you have more skilful players.

"Only one or two clubs have ever wanted to play four v four. There have been numerous occasions when clubs won't play us two games at under-11s, even though they come along to play eight v eight games with six or seven subs.

"I don't know why that's the case. We offer all the time. We don't just want to produce players for this club. We want to improve the standard of football in England. That was one of the reasons why the academy system was set up."

The challenge for United has become to find ways around the difficulties within the system. One way to broaden the base of talent has been to adopt a global approach to youth development, like Arsenal have also done in recent times. They now have recruits from China, Ghana, Togo, America and Brazil in their academy. "If you can't sign them at a younger age then we try and concentrate on countries who are still producing excellent football players," argued McClair. "It's easier in a way to get a foreign boy than it is to get some of the local boys into the academy."

The other way has been to seek more effective ways of developing the talent at their disposal. United have sought to shift the emphasis from physical and tactical development towards more skills-based coaching. As such, they have employed a skills coach, Dutchman Rene Meulensteen, to indoctrinate their new generation with the tricks and flicks of players such as Ronaldinho and their own modern skills disciple, Cristiano Ronaldo.

"We looked to a situation further up with the English boys where worldwide or European players had a better ability to beat opponents one v one," said McClair. "We tried to address that and we brought in a skills coach. There's evidence to show that the golden age of learning is roughly between the ages of eight and 12. If you put those basic principles and abilities into boys at that age, they maintain them. After 12, it's been proven that it's very, very difficult to change anything about them.

"The technical, tactical and physical become more important the older the boys get, but at an earlier age a lot of it is to do with skill factor, and playing. We believe there is a place for coaching but we also believe that there is a massive place for learning by playing. People learn from seeing other people doing things and the television and internet are fantastic avenues for boys to be able to see these images and then, hopefully, go out and practice them."

United currently have two young Scots in their academy, 18-year-old right back David Gray who made his debut in the Carling Cup earlier this season and 16-year-old left winger Danny Galbraith. Both players were signed from Hearts at 16, the age at which English clubs are allowed to pay a compensation fee to sign a youngster from north of the border, and are seeking to emulate countryman Darren Fletcher's route to the first team.

Galbraith, who is also making an impression at Scotland under-17 level, signed a two-year deal at Old Trafford in the summer and is revelling in the company of his boyhood idols. He cites Ronaldo and Ryan Giggs as role models and explains that the club's willingness to integrate all aspects of the club allow him to mix with them on a regular basis.

"One of the main reasons I went to Manchester United is because everyone mixes together," he said. "The first team and the youths all eat together and there is no distinction between the groups like there is at some other clubs. The boss has said that he regards every player at the club, whether youth or first team, as equal. So that means you can talk to players like Giggs and Ronaldo. They often come up and ask how you are getting on."

As a creative player, Galbraith speaks warmly of the club's emphasis on self-expression. "We are encouraged to run at players and take them on. If it doesn't work first time, then we are encouraged to keep on doing it. At Hearts it was more based on playing to instructions rather than expressing yourself. You will never hear one of our coaches shouting at the touchline.

"Perhaps at other clubs there is more emphasis on the team getting the result, but the only time when results really matter is in the Youth Cup."

Despite the academy system, United continue to set the benchmark in youth development.