The former United manager, now a club director and ambassador, says that Foulkes was a topic of conversation between himself and Sir Bobby Charlton only yesterday.
"I was very sad to hear the news," Sir Alex told ManUtd.com. "Bobby and I were talking about Bill yesterday on the way down to Cardiff. He was a really nice man and a great servant to the club, too.
“When I first came in as manager, Bill was managing in Norway and he used to bring players over to training at the Cliff. He came to training quite a lot and I got to know him well through that. He was such a nice, quiet man to know.”
Having risen up from the coal mines to the peak of European football with United, via the tragedy and turmoil of surviving the Munich air disaster, Bill’s place in club folklore is set in stone.
The defender captained a hastily-assembled United side less than a fortnight after Munich and, Sir Alex says, that courage made him a beacon during the Reds’ darkest hour.
“The story of his life was absolutely incredible,” he said, “and he’s assured of his place in our history by his appearances and by the way he performed, particularly in the aftermath of the Munich air disaster.
“Having gone through that, how he and Harry Gregg managed to perform a couple of weeks later, leading those young lads out against Sheffield Wednesday – and winning the game - was absolutely incredible. He was an exceptional man.”