Got talking to Juha on the chatbox about how best to remove the above from a sail.
The patch in question is on both sides of the sail, and is a very snug fit, with no loose edges or wrinkles.
I asked Juha whether there was any risk involved with peeling it off and he wasn't sure. Suggested that heating may help to soften the glue, but I'm wary of that.
Anyone else got anything to add?