Sail colour of the original prototype was ???

Small snippet of information on the early history of the Peter Powell Stunter. If you had asked me a few months ago what the original sail colour of the Peter Powell Stunter was, I would have said black, without hesitation. I had always been under the impression that in the early days the sail only came in black, and that later, blue, red, yellow and green sails became an option. Found out recently (with thanks to Paul and Emma at Peter Powell Kites) that prior to the black sail, the prototype for the Stunter had a clear sail, but these clear-sailed kites never went into production.

Unfortunately, none of these clear-sailed prototypes seem to have survived, and I couldn't find a picture of one through googling. So I can't post a picture, but in the absence of the real thing, you can easily imagine what it could have looked like against a blue sky, right?