Just to clarify a small misunderstanding. Castle Technology Ltd/Castle Technology Holdings Ltd/Tematic Ltd/Iyonix Ltd simply do not own RISC OS "lock stock and barrel".
This is simply because Pace themselves never owned RISC OS "lock stock and barrel" in the first place. You can only sell what you own. Most of the rights to RISC OS had already been exclusively licenced/sold to third parties before Pace became involved. Pace sold their interest in RISC OS, they did not sell on any third party rights in RISC OS because it was not theirs to sell.
Indeed I would be most shocked if any sale of RISC OS by Pace to any third party did not specify that it was sold "subject to and with with all the benefits of all existing licences of the Technology"