RONNY DEILA used to teach primary children.

He is now in charge of a group of professional footballers. As comparisons go, that's an open goal that even Peter van Vossen couldn't miss. After all, if you can handle a group forever squabbling, getting up to mischief and not doing as they're told.....then you can surely teach young kids as well. Boom, boom.

Deila's background, both as a teacher and as a Scandinavian, has clearly served him well at Celtic. He is big on discipline and establishing rules, but also on nurturing, encouraging and offering forgiveness and understanding. He is about as far away from the old school British football manager as it is possible to get.

Footballers being footballers will always chance their arm. And so Anthony Stokes was late back from a trip home to Dublin, Scott Brown had a night on the tiles ahead of a cup final, and John Guidetti went in the huff after not getting to take a penalty. Deila is aware of his players' misdemeanours and foibles but remains remarkably tolerant about it all.

He speaks candidly to his players. He occasionally raises his voice but not regularly. He does not like to impose fines. In fact, having established the ground rules, he prefers the players to self-police, which they do with great willing. He has a doors open policy and invited the players to come in and air their grievances. After early wariness, some players are now taking him up on it.

Deila doesn't have a motto but if he did it would be the one memorably mangled by former US President George W Bush: Fool me once, shame on you; fool me twice, shame on me (or you won't get fooled again, as Bush once told an audience). The Norwegian does not condemn mistakes, either on or off the park, as he believes it is only human to err. His beef, then, is with those who don't learn from their failings and continue to make them over and over, to the point that it becomes ingrained. Players like that, suggested Deila, won't be at Celtic for the long haul.

"Sometimes a mistake is made because they don't have knowledge about it," he said. "Young players experience new things all the time and I just have to be there. I can tell my kids that they can't drink but they will do it, I promise you. I just have to be there when they have done it. What do you learn from that experience? What do you do next time? If they keep on making the same mistakes then we have to do something. Hopefully I won't ever be in that situation."

He uses Stokes as an example of someone he believes has shown sufficient contrition over his apparent misdemeanour. The Irishman's punishment was to miss the home Europa League tie against Internazionale but since then Deila has tried to lift the player and he has responded in kind.

"Anthony is a good example," said Deila. "I've never yelled at Stokesy in my life. But I think he understands what I mean, you can see that. All of these boys are big characters, so you have to get them to understand what they want to do with their lives and how they are going to do it.

"Then you have to ask them the questions. What is the important thing in your life? If it is football, then how are you going to get the best out of your football career? Then you think and give the answers.

"Stokesy has responded really well in what he has done. He wasn't playing very well two or three games before the cup final, but he needed games and I said that if he kept working hard in training, he'd get his rewards.

"You saw in the League Cup Final. That is the best game I have seen from him so far since I've been at Celtic. I took that in front of the players and said: "This is what you get when you are 100 per cent". I am proud of Stokesy what he has done, but I don't need fireflies, I need stars. If you are good one game, that means nothing. I need people who are good all of the time, so you have to change lifestyle, not just change for a small period."

Dressing room discipline has become the jurisdiction of the senior players rather than the manager. "If they go beyond the rules we have they get fined," revealed Deila. "But they are fining themselves within the group and it is good that I am not a judge or something going round then trying to fine them. They do it themselves. They collect money and do it in a good way - and they love to do it. They have funny rules but also serious ones too. If you are just one minute late on match day then it will cost a lot of money. For a normal person it would be a lot of money. They are waiting and celebrating when someone arrives a minute late. It is a funny thing but I am overseeing everything. If I see that there is this attitude where an individual goes in front of the team then I will go in and do something about it."

There is a tolerance about making mistakes but only if lessons are learned from them. "Footballers are normal people. They don't like to let people down and they know when they do it. The stupidest thing as a leader is to go after them and punish them. This kind of leadership has gone now - it should never be in football. To frighten people to get better, if others want to do that, then do it but I will never do it. They are grown-up people.

"I've dealt with so many players who have had issues, but players that stay totally still and show no improvement? That kills me inside. I can't have them around me. That goes for staff, too. I need people who want to improve and learn from their mistakes and what they are doing.

"I'm not hard on mistakes. If you do a mistake and we lose a game, I never yell. But if you don't improve and make the same mistake again six months later, then you have a problem and I have a problem."