McCoist enjoyed great success playing under Smith during the club’s nine-in-a-row era before becoming his assistant in the Ibrox dugout after hanging up his boots. He was also part of the Scotland coaching staff during Smith’s time in charge of the national side.
Speaking shortly after the announcement that Smith had passed away at the age of the 73, an emotional McCoist said the news had left him devastated.
“He means everything to a lot of folk. He was my boss, my coach, my second father and then turned into one of my best friends,” he told talkSPORT.
“The loss is absolutely incredible.
“The good thing is he’s not in pain. I went to see Walter recently, I spoke to him at the weekend and we knew that it would be a matter of time.
“But it still does not take away the pain and the grief.”
McCoist, who is also close with Smith’s family, added: “At this moment in time, all I can think about is his wife Ethel, sons Neil and Steven and his grandkids. All Walter would have wanted is another few years to watch those grandkids play football and spend a lot of time with Jessica and them all, and sadly that’s the most painful thing right now.
“I could sit here and tell you about Walter Smith until the cows come home, about how good a manager, how good a coach, how good a football man he was.
“But what I will say is he was the best husband, the best father, the best friend – everything you’d expect in a man.
“It’s a tragedy today. I can’t tell you how devastated I am. Absolutely devastated.
“The history books will tell us how good Walter was as a manager and a coach, but I’ll tell you right now, what a friend, what a pal, what a boss, what a husband, what a dad, what a grandfather.
“That’s the message we should be thinking about. His family have lost somebody so close to them, so special to them and I just send them my love. I can feel their pain.”