Black Sabbath trade mark dispute

So Ozzy Osborne is taking action against Tony Iommi over ownership of the Black Sabbath trade mark. Considering that the band has been around for 40 years (almost that long since I saw them, at Newcastle City Hall), it's surprising that the UK trade mark was registered only 10 years ago, and a CTM five years later. It's not clear from the reports that I have seen where the action is being brought, or whether the UK registration or the CTM is what's in issue - or perhaps it's a US trade mark they are fighting over, though presumably they will all be dealt with on the same basis.

I'm interested because I am acting on a very similar dispute at the moment. The key piece of (UK) case law is SAXON TRADE MARK [2003] FSR 39, where the late lamented Mr Justice Laddie (as he then was) held that a group of musicians constituted a 'partnership at will' and that the name and goodwill were assets of the partnership rather than the personal property of the individual members...". This can cause problems when there are competing versions of the same band, which is not an uncommon occurrence, and what appears on the register might not reflect the real ownership situation. In the Black Sabbath case, though, it does look to me as if Tony Iommi has no personal right to the name on the basis of the SAXON case. Does this mean that he holds the legal title to the trade mark on trust for the members for the time being of the band? And what if he left it?