I am not a legal expert, certainly not in this area of civil and contractual law, but I would like to raise a few points and ask for comments, particularly of anyone who has more knowledge of such things than I have.
The petition is asking for an independent public enquiry. My understanding is that a statutory enquiry can only be ordered by a Minister. This seems very unlikely. A local authority can hold an enquiry, presumably at its own expense, though as it would not be statutory, I guess it could not force anyone to attend. It seems that this would make it an expensive talking shop of dubious purpose.
Is not the right way forward one of judicial review, if the FSB believe that questionable decisions have been made in the past involving a public body? They, the FSB, or the rumoured millionaire, would have to dig into their pockets though...