I have somewhere about six Shirley Wellard cassettes, I've had them for around fifty years, I have no idea where they are, I have moves house three times since I bought them, and since they don't work on my current cameras, and I no longer use bulk film, I can't be bothered to turn my house upside down to look for them.
P.S. I once met Ken Corfield who is mentioned in the Shutterbug article, he was later knighted for his services to photography and was then Sir Keneth Corfield, he was a very talented camera engineer who invented the Corfield Periflex camera that was mirrorless, had no prism and used a retractable periscope viewfinder.