Reading your post, Richard, I had to go back to the adhesive instructions and it does indeed say that you have to spray it on both sides. Duhhhh, I just couldn't remember doing it but Madame says that "Yes, we did, you klutz, do you not remember laying it out on the lawn out the back of the house !!!".
So I just stormed off with the cat and I'm now sitting in the car, in the cold until she calls me back in, out of sympathy. I just hope that she doesn't take too long as it's cold out here.