In reply to girlymonkey:
Now, if only I had a pair of old waterproofs!
I was really wondering if there were any patching materials that were hardwearing and sold in quite big sections with a sticky backing. However, that has to be one mean adhesive as the temp range they'll be used in is wide and the knee patches will go through a lot of movement as well as some abrasion.
A previous pair of cheaper waterproofs (that I finally chucked out) ended up with effectively this just from all the gaffer tape on them!
Post edited at 15:51