Ferguson admits that he is impressed by Smith’s achievements as Rangers boss.
“The resources at his disposal have been scant to say the least, but he has almost achieved a miracle in winning three titles on the trot,” he said.
“Wherever Walter goes, his experience is important.
“That has proved itself in the work he has done here in his second spell, with no money at all.”
United face Rangers in the Champions League at Ibrox on Wednesday.
