The young midfielder who came through the youth ranks at Albion made a number of appearances for United - and was rumoured to be part of the first team plans at Old Trafford this season.
However, he has been sent out on loan with West Brom winning the race for his signature.
After his cameo debut off the bench on Saturday - Jonny Drury and Lewis discuss how Albion landed Collyer, what the plans will be and who he could dislodge in the Baggies midfield.