Willie Miller was one of the best defenders of his generation.

The former Aberdeen legend captained the Dons to their greatest-ever triumph - the 1983 European Cup-Winners Cup win over Real Madrid - and knows a thing or two about the art of defending. It was Miller who turned defending into an art form and remains arguably one of the best penalty box tacklers the beautiful game has ever seen.

When Miller talks about central defenders you tend to listen. Miller has charted the rise and rise of McKenna since his development days at Pittodrie. This is why Miller believes that if Celtic were to recruit Scott McKenna on a free transfer they would be inheriting a defensive 'colossus' and 'man-mountain' who once put one over future Scotland international midfielder John McGinn when he was making a name for himself on loan at Somerset Park for Ayr United.

Miller insists that the capture of McKenna would be a 'no-brainer' for Celtic.  The 69-year-old knows that McKenna has the footballing pedigree to be a success with the Scottish champions and that Celtic boss Brendan Rodgers who is a huge admirer of the player would be recruiting a talented player as well as a top-notch person to boot.

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He said: "I've known Scott since he was a development player in the programme at Aberdeen. I have watched him grow from being a young lanky midfield player to this colossus who now plays as a centre-back. He has great grace and a real physical presence.

"I have watched him develop over the years and I remember he first caught my attention when he was out on loan with Ayr United and they played St Mirren. This man mountain that was Scott halved John McGinn in the middle of the park and I was working for the BBC at the time and was asked on air if I had anything to do with that. I had to reply no. When I was at the club, Scott was a slim midfield player and not the defensive powerhouse that he is now. He has reaped the rewards for working hard at his game.

"My memory of him as a development player was that he was a keen listener and learner. If he does go to Celtic, they will inherit not only a good footballer but also a first-class person. Scott has developed into a fully-fledged international player. He would be a real asset to any top club. Brendan Rodgers lays a lot of stock in his players being good people and it is really important. Any player who is brought to Celtic will know that thorough background checks will have been conducted. I can only speak for Aberdeen, I have known this club all my life and I know the people who work at the club and the standards that they set are impeccably high.

"Any player coming through from the development squad and who manages to make it into the first team at Aberdeen usually has good habits and is brought up with them. I am sure Celtic players are brought up the same way but looking at the kind of person that Scott is if he does sign for Celtic then he is not going to cause you any trouble and he is going to give you everything that he has got. He is a 100 per cent type player and he possesses a lot of ability and fantastic pace. He has developed into a real asset to anybody who can persuade him to join their club this summer.

"From that point of view, if Scott is on a free transfer then it would be a great move for Celtic if they could persuade him to come to the club and it is a bit of a no-brainer."

Miller believes that being a left-sided centre-back marks McKenna out as a rare breed in modern-day football. The 65 times-capped Scotland stopper can also envisage McKenna playing alongside American international Cameron Carter-Vickers and being the perfect foil. He admitted that he watched teams expose Celtic's defensive vulnerability and frailties from cross balls and set pieces last season, especially against his former club in the Scottish Cup semi-final at Hampden Park.

He reckons that Aberdeen and others would not have gotten so much joy if McKenna was at the heart of the Celtic defence because he is the type who would attack everything that is flung into the penalty box because of his aerial prowess and sheer brute strength.

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Miller said: "Left-sided centre-backs are rare in the modern-day game and Scott sticks out for that quality alone. Scott is a rare breed and he gives you the whole package. He is big and strong. He has a real threat at set pieces and he is very quick indeed and when you put all that together then it all adds up to him being a very good player.

"I watched Celtic struggle with set pieces in the Scottish Cup semi-final against Aberdeen at Hampden Park and I would suggest that is a weakness that everybody can see. They haven't addressed that yet and although Celtic do have very good players at the back the addition of Scott would add that height presence and physicality at the centre of the defence and that is so important these days especially when you are dealing with set pieces.

"Opposition teams have been relying on set pieces to try and get one on Celtic recently and they have identified that they are not the biggest at the back. The addition of Scott in that key area would help solve part of the problem because he does have that height, presence and willingness to go and attack the ball.

"Height is important in the central defensive positions. Cameron Carter-Vickers is quality and we all know that. Liam Scales has done very well and did a good job for Celtic. Liam is not the same kind of player as Scott and he played more as a wing-back when he played for Aberdeen. Scott would function in a two or a three-man central defence as he would never be asked to play in a wing-back role. That is not his strength as his strength lies in the middle of the defence. You could see Scott being a real asset to Celtic being deployed in a two or three-man defence alongside Carter-Vickers.

"I am not doubting that the work being done behind the scenes concerning Celtic and Scott could turn out to be the correct move for both parties. Celtic would be signing a quality player at the right age in the shape of Scott."

"Working with a coach of Brendan's quality would also bring the best out in Scott and that would enhance his future. Brendan's managerial forte is to take good players and make them better and he would do that with someone like Scott because he is always willing to listen and learn.

"The one thing he in his game that he may have to work at is his distribution. He has been working on his use of the ball as you can see he tries more and more to keep things calm and simple whereas in the past he was prone to bouts of rashness and tended to over-elaborate. That is not any kind of criticism of Scott, it is more of an observation but he has improved greatly in his distribution recently. Keeping things calm and simple would be the only area of his game that Scott should keep working on because the ability and capabilities are all there.

"He is 27 and that is a great age to get him. Celtic will know if they sign him that he will have his best years ahead of him if he does come to the club.

READ MORE: Why Celtic are interested in signing Flavius Daniliuc

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Having tasted the dizzy heights of Champions League football with Danish side FC Copenhagen last season, Miller knows that McKenna will crave to play on the biggest stage once more. Celtic have automatically qualified for the new Swiss model Champions League format and Miller believes that this is a genuine case when a player can enhance his international credentials by playing at the highest level for his club.

The man who made a club record 560 league appearances for the Reds said: "Scott would also be playing in the new Swiss model Champions League with Celtic and that could only serve to help and enhance his international prospects.

"He got a taste of those matches when he played for FC Copenhagen against Manchester City last season and that will have whetted his appetite to experience more of the same. Playing at the highest level with Celtic could also help Scott in his quest to become a permanent fixture in the Scotland national team. If Scott signed for Celtic he could test himself against the best that European football has to offer. Scott's career has been unpredictable at times but he needs to get himself settled down again and he could do that at Celtic by playing at the top level and he would right under the nose of Scotland coach Steve Clarke.

"As far as Scott is concerned, I feel that signing for Celtic would be a really good career move for him."