Gilmour, who has had a difficult loan season with Norwich City in 2021/22, struggled in the crucial World Cup Qualifier against Ukraine, and was ultimately taken off 68 minutes into their 3-1 defeat at Hampden Park.
In the aftermath of the game, Nicholas urged the 20-year-old to pick up his socks, taking a somewhat unnecessary swipe at the Owls captain along the way.
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Writing in his column in the Daily Express, Nicholas said of the Blues youngster, "Billy Gilmour is a talented player, but if he is not careful he could end up becoming the next Barry Bannan… Gilmour is a tidy footballer but he has to offer more and we need to stop making him out to be our saviour.
"He struggled in the play-off because he didn't get on the ball enough - and when he did it was square pass, square pass.
"Let's hope he can make a greater impact than Bannan - another physically small midfielder who did okay for a few seasons but failed to hit the heights everyone hoped."
Bannan is a player that has been coveted by teams across the divisions in English football over the past few seasons, and has just finished a campaign in which he won Goal of the Season, was nominated as Player of the Season, and picked up numerous individual awards along the way.
The 32-year-old hasn’t been given the chance to play for his national team since 2017, but in that time has gone on to become a modern day Owls legend.