Well, I took both the FW and wheel with hub to a Giant cycle store and had a chat with the mechanic there. He himself was a little stumped too. Visually comparing it against an ISO threaded FW from the shelf, the thread spacing on my FW looks marginally wider so we assumed it is French. He explained that Cyclo as a company have changed several times over the years and are currently manufacturing tools so searching on their website didn't help sadly. I think I'll return the FW to the hub and sell them on complete, then purchase an ISO freewheel when the replacement wheels arrive.
Thanks again everyone, you've been a great help.

Adam