It's probably mostly of his own stuff, and stuff borrowed from other people or companies for the show - or possibly hired. Don't forget that back then, pro keyboard players pretty much needed big rigs, so this kind of thing was common for a working professional in a name band. Knowing how much the BBC paid for BBC2 educational programmes (basically nothing!), no one's itemising the cost of a brand new JX10/CZ1/Memorymoog/MC500/etc on the BBC budget sheet, for sure!
Lol! Yes it"s true BBC 2 was the poor relation in budget terms. A lot of the gear could have been manufacturer supplied as it was notoriously difficult to get product placement on the Beeb back then - they even used to tape over large keyboard logos on TOTP - now seems very silly. They couldn"t really do that on Rock School given what it was.
In fact a friends older brother was the frontman for an essentially 'punk' band that made it to TOTP briefly a few times, back in the day. Although a guitarist, (spit!) , he was inundated with offers of freebies, everything from strings, pickups and various clothing brands wanting to be 'seen' on TOTP which was then the 'holy grail' in the UK - seems strange now looking back at what it actually was by then, mostly a very badly mimed joke. It was really guys like Jools who eventually made live playing an essential with his 'Later With' progs.
My comment about it costing an arm and a leg was more relating to any mere mortal (like me!) wanting to buy the same.
What you said about pro players 'needing' a big rig was true as it became a bit of a 'mines bigger than yours' thing.
Rick Wakemans rigs were astonishing, but then, he could really play 'em good too!