On the subject of new London discoveries, Jimmy Soul's "Twistin' Matilda / I Can't Hold Out Any Longer" (HLU 9549) was apparently discovered to exist as a London demo only a couple of years ago. The number was first thought to have been allocated to an unissued Bill Smith Combo single (according to Paul Pellettier's London discography). Since January 2012, only two or three Jimmy Soul demos on London have come to light, and no stock copies have been found yet.
Like Darrell Banks, it was later relased on Stateside (SS 103). Similar 'injunction' problems with SPQR rights, as there were with Revilot, maybe?
https://www.45cat.com/record/hlu9549uk
https://www.45cat.com/record/ss103