A year ago, if you took a poll of Scottish fans over who they would rather have at left-back for the national side, Kieran Tierney would have won hands-down. Now? Even England fans would probably have Andy Robertson playing there for the Three Lions over any of their current lot.

That’s no slight on Tierney. The Celtic youngster has been magnificent again this season, but the way that Robertson has flourished since breaking into the Liverpool side has been incredible to watch, and hugely exciting for the Tartan Army.

You simply need to have both of these players in any Scotland side, and that’s where Kieran Tierney’s flexibility comes in handy, as he will likely play on the left of Alex McLeish’s back three, with Robertson marauding up and down the flank.

That will of course blunt the attacking threat of Tierney, but the fact that most Scotland supporters would now probably agree that is a price worth paying to play Robertson in his best position, speaks volumes for the impact the former Queen’s Park player has had since his move to Anfield.

A couple of weeks ago, I wrote a column in our sister publication, The Herald, that argued Tierney would not have his head turned by reported interest in him from Manchester United, and he would not likely be tempted to agitate for a move to England – perhaps at any stage in his career – because of his love of Celtic.

I stand by that. The player loves life with the Scottish champions. But he would need superhuman powers of focus if he didn’t cast at least a glance at his Scotland teammate as he starred in the Champions League quarter-final against Manchester City, and thought; ‘what if that was me?’

Given the financial gulf that exists between Celtic and sides from the major European leagues, Tierney is highly unlikely to even get a sniff of such a stage in that competition in a Celtic jersey. At what stage does he become too big a fish for the Scottish pond, and want to grow as a player elsewhere?

Given his ties to the club, he may want to see out the bid for 10-in-a-row, but what else can he realistically achieve beyond that?

It should be noted of course, that the manager Tierney is currently working under knows a thing or two about developing young talent. The improvement in a plethora of Celtic players, not just Tierney, since Brendan Rodgers’s arrival has been more than worthy of the praise it has received.

But I just wonder if there is a glass ceiling on how much Tierney can learn in a practical sense playing week-in, week-out against, with all due respect, the players who make up the rest of the Scottish Premiership. The mixture of these sides, up to and including Rangers, tends to be a mixture of young Scottish products and players signed from the lower leagues down south, or the fringes of English Premier League outfits. Look at what the big stage has done for Robertson, a player who not so long ago was plying his trade in front of two men and a dog for the Spiders.

Tierney is a better player now than Robertson was at his age, so just imagine his potential if he was thrust into an environment where he is playing with and coming up against genuinely world-class talent on a regular basis, not just a handful of times a season if Celtic make the Champions League group stages.

It may all be a moot point, and no harm to Tierney if he does wish to stay a Celtic player for life. It could be argued that it would be a refreshing change from the mercenary attitude that prevails in the modern game, and in all likelihood, he would go on to become a legend at the club he has supported since he was a boy.

I can’t help but wonder though just how good he could really be, if one day, this precocious talent flew the nest.