EVEN football's greatest rogues and chancers have never coughed up the excuse Stuart Armstrong might use if he turns up at the training ground looking bleary-eyed this morning.

To put it in a nutshell, Armstrong signed for Celtic and immediately prepared for a long night when he wouldn't have time to think about football.

All this palaver about leaving Dundee United for Parkhead had distracted him from a pressing engagement over the past few days. Forget signing deadlines, he is taking a degree course in employment law and was given a deadline of today for a 2000-word essay on redundancy.

As of yesterday afternoon, when he was blethering away about transfers and cup finals, he hadn't written a word of it. It would be easy to imagine Armstrong being Ronny Deila's kind of guy even before the Celtic manager saw him play (when he did, he publicly compared him to another tall, blonde midfielder, Germany's Thomas Mueller).

The 22-year-old's intelligence and manner are as impressive as his play and he isn't likely to give Celtic any problems over the course of his three-and-a-half-year contract. Even if he is a little tired when he shows up at Lennoxtown today, Deila will enjoy the explanation for it.

"I have a law essay due tomorrow that I have not started. I think you get about a month to submit these things but I usually leave it until the last minute, that's my style. I'll go from here and start writing."

The cliche has it that footballers fritter away their spare hours shopping, or gambling, or generally standing around with their mouths hanging open. According to Armstrong a combination of boredom and plenty of free time persuaded him to embark on an Open University course which still has two-and-a-half years left. "I think it's important to focus on other things than football some time. It's a good distraction and it's worthwhile."

Not that Celtic signed him for any academic qualities. He is at Parkhead because of his movement, awareness, technique and imagination on a pitch, where his passing and goalscoring have graced United's midfield since making his debut in November, 2010. If Deila continues his preferred 4-2-3-1 formation Armstrong would be comfortable in any of the three forward positions, although he would be more likely to displace Kris Commons on the right than Stefan Johansen in the middle.

Gary Mackay-Steven, his fellow new recruit from Tannadice, is likely to offer an alternative to Anthony Stokes on the left. Armstrong laughed when reminded of Deila's quotes from earlier this season, comparing his style to Mueller's: "I'm going to have to step up my game on the training ground, the manager might be disappointed when he gets out there." In fact, Armstrong is an impressive enough guy for Deila to be confident that he has landed a real talent. Armstrong outgrew Dundee United and it seemed he would follow Ryan Gauld and Andrew Robertson by moving out of Scotland without stopping at the country's wealthiest club. In the past he had hinted about wanting to try English football.

"I think every player has ambitions there but I never said England was my sole target. It became apparent Celtic were very interested and when a team shows that level of interest and follows up on that it is very flattering. A massive club like this is very hard to turn down. The competition for places here is a challenge I think that you have to embrace. It's such a big club and you have to be up for the challenge, trying as hard as I can to show my ability." The lure of Celtic can be irresistible for most Scottish player although for Armstrong and Mackay-Steven there was a complication. Moving now rendered both of them ineligible for the League Cup final, denying them the possibility of lifting their first major medal next month. Both decided to play the long game, with the understandable expectation that many more medals and cup finals will come playing for Celtic rather than United.

"After the joy of getting through the Aberdeen semi-final it was disappointing not to be part of the final," said Armstrong. "But in the long-term I think I'll have a lot more opportunities in finals at Celtic. The League Cup final will be quite a strange one for me. It was difficult to leave United given the people I had met along the way. I had a lot of friends and long-lasting relationships because five-and-a-half years is a long time." United's manager, Jackie McNamara, was supportive to the end.

"I wouldn't say he actively encouraged me to go but his sole focus was on whether I would be happy and whether or not it would be good for my career. He's been huge in my development, what with the freedom he gives his boys to play. He'll never criticise for you making a mistake when you are trying to make an attacking move. It's very important to have that creativity. It feeds confidence." Deila will also know how to get the best out of Amstrong as well, if he's done his homework. As for the player, he had a late night doing his own.