Bale is one of the hottest properties in world football after taking the Premier League and Europe by storm in the past 12 months.
He is now an integral member of the Spurs side, but he was a target of Ferguson some five years ago and a bid was lodged with Southampton.
Ferguson does not know the full scenario as to why their bid failed, but he saw the Wales star slip through his grasp and head to the side he will lock horns with on Sunday: Tottenham.
"We tried to sign him as a 16 or 17-year-old boy," reflected the United chief. "Southampton had a Scottish chief executive and George Burley was the manager.
"I don't know the full circumstances but they didn't accept our offer and I think they must have alerted Tottenham."