adamr wrote>"Martin could presumably done it all using BBC Basic for Windows? After all one of the companies is using VRPC to run his program. "
If you're following that logic why bother with RISC OS/BBC BASIC at all - there's lots of other development environments on lots of other platforms (but of course that would even be *more* irrelevant).
If Martin has managed to get RISC OS (the operating system) and native hardware (A9 in this instance) to be purchased to run it all the better. Turnkey solutions often consist of a hardware platform + OS + specialist software the end customer may not know (or more likely less care what it runs on) so long as it "does what it says on the tin".