James Craig, the former Scotland winger, has become the latest rugby player to reveal that he has developed a serious condition as a direct result of head injuries suffered while playing the sport.

Part of Glasgow sporting royalty Craig was the most successful of four sons of Lisbon Lion Jim who took up the alternative footballing code on attending St Aloysius College.

However having suffered from hallucinations since 1999 he was finally diagnosed as having a bipolar disorder only last year and is in no doubt that his illness, which has brought swings from manic episodes to sustained suicidal tendencies, is a direct result of collisions on the rugby field.

“Over the course of my career I had a minimum that I can remember of 15 head injuries,” Craig told HeraldScotland.

Read more: "My behaviour started to become erratic ... Lots of highs, lots of lows" 

“Whether that was being fully knocked out or getting a bang on the head and double vision or being hit hard where you get to that point where you’re groggy.

“A lot of the times you don’t own up to these things, you know, you get up and you play on.”

Craig played for Glasgow and Rotherham before retiring due to a leg injury 11 years ago and is “100 per cent” sure he never received any advice about the potential consequences of head injuries in what were the early days of professional rugby.

“I think there was an ignorance,” he said.

“We knew that if you had a head injury you were three weeks out, but we were never tested in that three weeks.”

That, Craig reckons, was down to a combination of the macho culture that is prevalent in rugby and fear of the implications for earning power.

“It was definitely about being seen to be hard and the flip side was the selection process of getting picked for Glasgow or Scotland A or Scotland itself,” he noted.

He has not turned against the sport.

“I don’t regret ever playing rugby and I don’t regret ever being a professional rugby player but I wish I’d taken a bit more care of myself, especially with regards to the head injuries,” he said.

However he is aware that this a burning issue for rugby and while he is doubtful whether former players will take similar action to that in the USA where huge pay-outs are being made to former NFL American Footballers who have suffered similarly as a result of head injuries, he suggests the sport owed its practitioners more of a duty of care, saying simply: “There probably should have been more cognitive tests done for us after being concussed.”