Few of those who closely watched the development of Liam Miller over the six years he has been at Celtic ever seriously doubted the young midfielder's ability to make a major impact at the highest level of the game.

Fewer still, though, could have expected that the Corkman's fortunes would have been transformed quite as dramatically as they have been over the last six months or so of his Parkhead career.

Originally spotted while playing as an under-14 for Ballincollig Boys Club by Mick Conroy, the former Celtic defender who now coaches in Cork, the youngster immediately impressed the club's youth team officials when he went to Glasgow for a one-week trial.

Having signed for the club he had supported as a boy in October 1997, he made steady progress through the underage ranks with Willie McStay marking him out as someone who was a "little bit special".

Miller made his first team debut on the last day of the season back in 2000 and was expected to make a bit of an impact during the campaign that followed. Instead, hampered in part by injuries, he remained a peripheral figure, making just one more appearance in the 12 months that followed.

A six month loan spell in Denmark with AGF Aarhus followed, at the end of which Marc Rieper, the former Celtic player then managing the Danish outfit, came close to landing the youngster for just £300,000.

Brian Kerr recalled recently how he had talked to both Miller and members of his family at that time regarding the player's growing frustration at his lack of progress, and Miller returned to Celtic Park in the hope his chance would finally come.

Kerr, a long-time Miller enthusiast, has more than once observed that Martin O'Neill had done well in the way that he had brought the player on, but under-21 manager Don Givens, who described the Corkman as, "one of the best, if not the best, players I have ever coached," urged him to move on at one point last season.

It remains unclear whether Miller's eventual emergence as one of the stars of this season was the result of O'Neill's long-term planning or a lucky break, but John Hartson's observation - after Miller had come on as a substitute during a game in the United States last summer - that, "everybody realised that this boy could play," suggests that if the manager had earmarked Miller for great things some of his more established players were unaware of it.

Since then the club's stars have taken it in turns to heap praise on a midfielder for whom the moniker "The New Roy Keane" must have already become a little tiresome.

Henrik Larsson has described the Irishman as "one of the best young players I have ever seen" and things became slightly comical when former Celtic and Scotland skipper Paul McStay said that it was "a compliment to be talked about alongside Liam".

In more than 30 appearances for the Scottish league leaders this year he has more often than not lived up to the hype, with many of his best performances coming against the better sides Celtic have played in Europe.

His departure will come as a significant blow to a club where one director had recently emphasised the importance of developing talent from within because, he said, the days of buying it in for millions of pounds had passed.

While the point at which O'Neill realised his full potential may be in some doubt, the record of the man who will be his manager at the start of next season for making bright prospects into shining stars is not even open to question.