But he admits Scott Brown had a far greater burden to carry after making the same journey for £4.4million a year later.

In recent weeks Brown has consistently produced the energetic and creative displays that persuaded Celtic to pay a record transfer fee between two Scottish clubs.

Caldwell believes his team-mate has been able to lift his game as he discovers how to cope with the pressure that comes with such a huge fee.

And the defender is full of admiration for the way Brown, 23, dealt quietly with personal tragedy while adjusting to life with the Old Firm.

"I played alongside him when he was a lot younger but the experience you get here, playing in big games week in, week out makes you better," Caldwell told the Celtic View.

"With him coming here for the price the club paid for him, he had to cope with more expectation than I had and it's perhaps been a bit more difficult for him to find his form.

"But as Scott has got the experience and learned how to play for Celtic, he has got better and I am sure he will get better in years to come.

"He is still very young, but has every attribute needed to be a real top player and he has proved that."

The midfielder has scored in Celtic's last two games, against Dundee and Aberdeen, after making the sort of runs into the penalty area that made his name at Hibs.

And Caldwell predicts there is much more to come from his fellow Scotland international, who has been linked with moves to Portsmouth and Manchester City in recent weeks.

"In the game against Dundee he dragged us back into it in a 20-minute period when we were struggling," Caldwell continued.

"He was everywhere and his performance got us back into it.

"As a footballer you should never stop learning. You should always want to get better, to keep working hard and he is at the perfect club to do that.

"He has a manager and group of coaches here who can help him and bring him on as a player and I am sure he will get even better as the years go by."

Brown had his critics towards the end of last season but played his part in Celtic's third successive title triumph.

Days after Gordon Strachan's men pipped Rangers to the post with a 1-0 win against Dundee United, Brown was mourning the death of his younger sister Fiona, following a long battle with cancer.

"A lot of us didn't even know what was going on in Scott's personal life last season," Caldwell added.

"He came in, did his job and worked as hard he has ever done through a really difficult period.

"I can't even begin to imagine or understand what was going on in his head.

"But he came through it and showed his strength of character."