Six-year-old Kate Kellock took the news badly.

"When I told my wee girl I was retiring she started crying," said father Al. "I asked why she was sad and she said it was because I wouldn't be captain any more. She said she liked it when I led the team out."

Older Glasgow Warriors fans might be able to stem the tears, but they will feel a grievous loss when Kellock takes his leave of the team at the end of this season. Through good times and bad - more of the latter to begin with, more of the former just recently - their 6ft 8in captain has been a towering figure in far more than the obvious sense.

Those Warriors supporters have often been divided on the issue of Kellock's qualities as a player - although you might think that 56 Scotland caps would settle those arguments conclusively in his favour - but there is no scope for discussion of his merits as a leader. Without question, he is the best this country has produced in the professional era. Taking the wider historical view, he stands comfortably alongside the likes of David Sole, Jim Aitken and Ian McLauchlan.

Perhaps the greatest tribute to his talismanic influence is in the fact that he has, in a sense, made himself obsolete at Glasgow. Fiercely competitive and fiercely proud, he will be fighting for his place to the end of this season, but he has successfully mentored a generation of players during his nine seasons with the club. Would Jonny Gray have become the figure he is now without Kellock helping him along the way?

How ironic, then, that it was Gray's arrival during Glasgow's remarkable 34-34 draw with Leinster in Dublin last Friday that convinced Kellock that his decision to retire was the right one.

"It's a decision I'm comfortable with because I know I'm ready to go," he said, "but is not a decision I ever wanted to take. In a way, I feel like I'm doing something that I don't want to do, but I know this is right for me. I knew that after 51 minutes of our game against Leinster last weekend when young Jonny Gray came off the bench. You see a guy like that come on and you know that it's time."

In time, Gray may become as much a leader as Kellock has been, but it's fair to say that bar has been set pretty high. Towards the end of last season, Kellock seemed in danger of becoming a peripheral figure for the Warriors, but Gregor Townsend had no compunction about bringing him back for the sharp-end games that really mattered, the PRO12 semi-final against Munster and the final against Leinster.

The first game was a narrow, though heroic, win; the second a heavy defeat. In both, though, Kellock's gifts shone through. At a time when Scotland players are being questioned for not taking responsibility on the field, Kellock stands as a beacon. It would be an understatement of comic proportions to say that he simply enjoyed the leader's role; in reality, he relished it.

Some referees might look forward to a quieter life in the future, but Scots in general, and Glasgow Warriors followers in particular, should pray that someone with a fraction of Kellock's ability to manage game officials turns up soon. And pray harder for a captain who can channel his own intensity into a team as brilliantly as he has.

Those who have come to the Warriors in the Scotstoun years do not carry the scarred memories of earlier days. When Kellock arrived in 2006, the team was itinerant, its facilities ramshackle, its performances hopelessly inconsistent. Inch by inch, little by little, he changed the culture of the club into something more purposeful and more successful. Former coach Sean Lineen's wisest move was to bring Kellock back from Edinburgh; current coach Gregor Townsend's smartest decision was to wield his new broom lightly and to keep Kellock as captain.

We will miss that piratical grin, those finger-wagging team talks, those censorious glances at players - not all of them called Niko Matawalu - who have just done something daft. There will be a big gap, and a very tall gap, in the Glasgow dressing room when this season has ended. And Kellock admits there will be a gap in his life as well.

"That will be the bit I miss most," he said, the emotion obvious in his voice. "I love that time before a game when everyone is on the same page and very focused, when my job as captain is to narrow that focus to a few essential things. There's nothing more powerful for me than to be standing in that huddle with 15 players, all knowing that you're going out to do a job.

"The feeling after a win is superb, but sometimes even after the losses as well. What I say to the lads before every game is that we want to come off and be able to look each other in the eye knowing we've given our absolute all. That's all you can ask."

And all he has given. The boy from Bishopbriggs has Glasgow blood coursing through his veins and he will carry on holding the torch for the city's rugby as an ambassador for Scottish Rugby and as a mentor to up-and-coming players.

Even yesterday, as he started to count down the days to the end, he was talking enthusiastically of the young stars who will carry things on for the Warriors. There was something close to paternal pride as he reeled off the names of those who turned up raw and wide-eyed but have since turned themselves into Test players and their team into a respected force in Europe.

It is up to them to carry on the good work. They have very big boots to fill.