"His talent was unquestioned. I remember he played against what was a Dundee reserve side with a number of first-team players in it.
"I’m looking at Billy who was 15 and thinking there is a health-and-safety issue here because he was so slight. But he went out and absolutely ran the show.
"He had trained with us a couple of times in the first team and I am really pleased to see how he is doing now. What a talent. I think Scotland have a future world-class midfield player, I really do.
"I think he is going to keep on improving because he is in a great environment with Frank and Jody (Morris, assistant manager) and the players at Chelsea.
"I very much hope he can continue that progress because, if so, Scotland truly will have a world-class midfield player there."