Thought I would call in a tack shop in the town near me on my way to the yard today, I've heard lots about it but never been in. So glad I did! They had a second hand 4'6 Masta HW stable rug in, just back from the cleaners, £25! 
The "growing room" is free
(no prizes for guessing the purple one was an underrug!)
Toasty ears:
The "growing room" is free
Toasty ears: