PERHAPS it is his age which counts against him: he will be 30 later this year.

Maybe some managers and scouts see the limitations in his game - his passing or the infrequency of his goals - and amplify those flaws in their minds. Or it could be his obvious commitment to Celtic which acts as a forcefield around Scott Brown.

Whatever it is that prevents other clubs from testing Celtic's resolve with significant bids for the captain of club and country, no-one around Parkhead is complaining.

When there is speculation about Virgil van Dijk or John Guidetti, or occasionally James Forrest or Kris Commons, Brown operates in a vacuum of silence. In the distant past he was linked with Portsmouth and Tottenham, who were said to be prepared to pay £9 million for him. In 2011 Newcastle valued him at £6m. Inter Milan and Juventus were reportedly interested too, and later Crystal Palace.

Throughout all of this Brown serenely carried on at Celtic, neither openly trying to encourage interest from elsewhere nor appearing to use it to his advantage in contract discussions. He committed himself to Celtic again only two months ago, signing a contract extension which ties him to the club until 2018. By then he will be 33 (still three years younger than Manchester City's Frank Lampard is now).

Neil Lennon made Brown the Celtic captain and nearly two years ago Gordon Strachan afforded him the same distinction with Scotland. Both have regularly described him as the man who set the tempo in their sides. At £4.4 million he is the most expensive signing on the books at Parkhead and has played over 300 times including more than a half-century of European ties.

At international level he is only eight caps short of 50 and a place in the Hall of Fame. It all adds up to a considerable curriculum vitae, yet speculation about him leaving never takes hold. According to Ronny Deila, the fourth manager he has served at Celtic since 2007, Brown does not get properly wooed because he has consistently given off a single, unchanging message: I'm happy where I am.

"I think if Scott Brown wanted to move he would get a lot of clubs," said Deila, ahead of Celtic's lunchtime SPFL match against Ross County in Dingwall. "That wouldn't be a problem, but he is so clear that he wants to stay at Celtic and have his career here. He has signed a new contract. He has had options before - I have talked to him about that - but I think he is not sending out a message that he wants to leave. I'm very glad about that."

Brown's career path should never be confused with a lack of ambition, said Deila, despite the inevitable view that he could have challenged himself further by moving to the Barclays Premier League or a major league on mainland Europe.

"He plays for Celtic and he wins games. He plays in the Champions League against the best teams in Europe. He is winning trophies. I think a lot of players should go that way and think that way. When you are happy, why should you go to another place to try to do it differently? Here, there are always challenges to win because of the expectations.

"I think he could adapt to whatever level he was going to. That's down to his attitude on the pitch and off the pitch. It is so vital to the team and you can always rely on him. He almost never makes a defensive mistake. He is like a dog in the midfield. He chases and if people make mistakes, he is there at once. His presence...every team needs a player like that. Every day in training he gives 100 percent. He is the role model in the team. We have more players like that - Charlie Mulgrew, Mikael Lustig and Stefan Johansen. All those guys are always looking forward and if you get the whole team to go like that, the results will follow."

Celtic's form has stabilised. After taking one point from an available six they have rallied to win three-in-a-row. Their last stutter came against Ross County at Parkhead, a goalless draw two days after Christmas, and now the clubs face an early rematch in the Highlands. When Celtic were there in August they won 5-0.

There have been eight goals in their last three outings including an unusual quartet from full-backs Emilio Izaguirre, Adam Matthews and Lustig, who only played for 45 minutes against Motherwell on Wednesday yet scored twice. Had he been tormenting strikers Guidetti, Commons, Anthony Stokes and the other usual goalscorers about eclipsing them?

"They were my first goals in years so I think I'm quite stupid to start boasting about it! Of course it's not every day you score two goals but let's be honest, I don't think I'll be up there in the scoring charts at the end of the season. I had a chance to get a perfect hat-trick [he scored with his left foot and with his head then hit the bar with a right-footed shot]. It was a once in a lifetime opportunity. I blew it!"

Charlie Mulgrew aggravated a knee injury while playing for the development side on Wednesday and is not likely to recover in time for the League Cup semi-final against Rangers next weekend. Otherwise Celtic head to Dingwall at full strength.