The rise of Charlie Mulgrew has been an effort to overcome scepticism.

There were doubts when he returned to Celtic 19 months ago, and his initial appearances in Neil Lennon's side were unconvincing. Mulgrew was susceptible to his own reservations, too, and declared before he left Aberdeen that "centre-half just isn't my position". The impression was always of a talented player who understood his ability, but not always how best to deploy it.

Nobody considered that Lennon would build his new defence around Mulgrew. Now the Celtic manager moves him around the back four to ensure that he remains involved. Mulgrew has developed into an integral figure, and fans have devised a song in his honour. There is always a greater tendency to cherish players who share the support's background, and there was genuine sentiment in the way they sought to sustain him following the death of his father last November. Being a Celtic supporter is not the sole cause of Mulgrew's popularity. There is recognition of his dogged refusal to accept a limited role.

Mulgrew might have felt condemned by his faltering displays early last season, and the emergence of Emilio Izaguirre as a dynamic left-back. Being played at left midfield in an Old Firm game at Ibrox told of Lennon's faith in the player, but it is a grasp of his defensive obligations that has brought Mulgrew to prominence. Craig Levein has eventually come round to the player's merits, and Mulgrew's call-up for the friendly against Slovenia is his first for the senior squad, even although the 25-year-old was previously established in the under-21s, winning 11 caps including one against the Slovenes.

"All Charlie had to believe in was that he was a defender, because he's such a talented player going forward," says Scott Leitch, who was assistant manager at Aberdeen while Mulgrew developed into a coveted defender.

"He had to change his mindset, and since he's done that he's been superb. He's really quick over the top, he can read the game. Charlie knew he could play centre-half, he just really enjoyed going forward, he was such an attack-minded player. It probably needed him to go to Celtic and play as well as he has done to understand that he can be a really talented centre-back."

Gifted players are often prone to being oblivious. They are able to rely on their natural aptitude without cramming on other aspects of the game. Mulgrew joined Celtic at 12, and four years later he was already turning out for the under-19s. There was precocity to Mulgrew, and, as captain of that side, he later led the team to a league and cup double, but from a variety of positions.

He did not follow the likes of Shaun Maloney and Aiden McGeady so readily into the first team. Gordon Strachan felt there was too much naivety in him for a defender, and sent him to Dundee United on a loan spell. "We know he can attack, we know he can cross the ball," Strachan said. "He's just learning how to defend a wee bit better. It's the kind of thing that all young Celtic defenders need to learn. They attack so much in the youth team and the reserves that they actually don't know how to defend."

He often played in midfield at Tannadice, though. Mulgrew had to leave Celtic permanently then return again to realise his potential. Injuries scuppered his time at Wolverhampton Wanderers, but under Mark McGhee and Leitch at Pittodrie, he restored his reputation. The sense now is of a player at ease with his place at Celtic. There are occasional relapses – Mulgrew was culpable for one of the goals that Kilmarnock scored as they led 3-0 at half-time at Rugby Park last October – but he also scored the equaliser.

There is prowess in the way he delivers the ball, and some of his goals this season have been striking. It is more impressive to note that he is robust in the air, reliable in his positioning, and less vulnerable to periods of distraction. Lennon has been talking about Mulgrew deserving international recognition for some time, but it wasn't to improve the player's mood. Mulgrew's development has been admirable.

"With Charlie's passing ability, it helps the way Celtic play," Leitch says. "They like to pass the ball and move it quickly. He can do that, but he's also a very good defender. Charlie believed that he was good enough to play for a club like Celtic. He's been one of their best players this season and that's down to his character. It was a difficult start for him, but he showed his maturity and his belief in his own ability. The level he's playing at just now justifies the call-up he's received to the Scotland squad. It's down to Charlie's hard work and determination to succeed."