It turns out that the vet has told the collie that she could do with losing a little weight.  As a result it was suggested that Mum filled her up with carrot.  As I can be prone to putting on weight if not strictly monitored, the carrot thing was extended to my feed bowl.  Attempt 1 was raw carrot.  We both took exception to this and made our displeasure felt by setting carrot traps around the house.  This consists of removing a piece of carrot from the bowl and strategically placing it for the unwary to slip on.  Sadly Mum realised and retrieved them.  She has found the piece on the stairs easily, along with the piece in the yard just outside the back door. The three bits that were strategically hidden in the long pile of the lounge carpet were a little more challenging and took her longer to find.  We managed a further two in the dining room and one at the top of the stairs.  We scattered four pieces as an obstacle course around the kitchen.  Attempt 2 was cooked carrot, mixed with dog food we scoffed the lot, and very good it was too.  Hopefully she will pay heed.