Johnston says the Scot is a man who knows Liverpool Football Club better than anyone.
"The fact that he didn't go and live back in Scotland or abroad after finishing says much about how he feels for Merseyside," Johnston told LFC Weekly.
"Every time he goes for dinner, every time he goes out of the house, somebody from Liverpool will say something to him. When he's on holiday - when he's on the golf course, he will be approached by people wanting to talk Liverpool.
"Speaking to him, I've always got the impression that he's waited for this day since he left Liverpool originally.
"So it's a case of getting hold of the pit helmet, switching the light on and jumping back into the coal mine."