As mentioned earlier, I have written to the people who compiled the Red List and we have exchanged a few emails, the latest of which is copied here, with their permission.
Hi Les
Aha, I think this might be partly a misunderstanding. Though we've got woodturning on the Red List doesn't mean we think that it is in endangered. It's in the most viable category, alongside things like knitting which is done by hundreds of thousands if not millions. We know that woodturning is amongst the most healthy crafts in the UK. The intention was to assess all crafts, rank them by their level of endangerment, and then do work from that to move as many of the endangered ones as possible into the viable category through support, awareness raising etc. Maybe we need to explain this better on the website!
These figures though estimates are useful and will help me a great deal when I come to update this in September.
Best wishes
Daniel