Huuuuuuuuuuuge thanks to Heidi- the vinegar worked! We think he found the UHU glue, which sticks to everything anyway!
I didn't really want to applique over the mess as it is a quilt that my Auntie made. Still, I didn't get cross with the little man, it was an accident, but he did get a very gentle reminder that when we use glue, we put newspaper down first lol!
So... God bless white vinegar!! (and all of you for your suggestions, many thanks everyone)