'The Ultimate Illustrated History' by Phil Sutcliffe (the 2009 edition, at least) only mentions that the song was inspired by a painting. It doesn't say anything else.
'The Early Years' (by Mike Hodkinson) and 'The First 12 Years' (by Mike West) only mention its title and say nothing about it.
David Minns, George Tremlett, Larry Pryce, Lesley Ann Jones, Peter Freestone and Rupert White don't metion the song at all.
Georg Purvis certainly does, as his (fantastic) book has a section going through each and every song, but I can't find my copy and, off the top of my head, it doesn't mention anything 'new' about this song, only the stuff I already told you about from audio and magazine interviews or Brian's website.
No idea about 'As It Began' since I lost my copy a decade or so ago... and 'Is This the Real Life' probably also regurgitates the same info you can find elsewhere (e.g. Wikipedia).
John hated Hot Space. Frederick's favourite singer was not Paul Rodgers. Rog didn't compose 'Innuendo.' Witness testimonies are often inaccurate. Wales is not in England. 'Bo Rhap' hasn't got 180 vox.