An awful lot of these WERE played - Los Bravos at Peterborough Fleet early 80s, Len Barry certainly at The Scene and therefore almost certainly at the Wheel (a guy on here posted his memories a while back and made a point of saying his tracks were massive), Holland & Dozier - Pete told me the instrumental was played (I'm presuming the Mecca or Ritz - anyway he bought it back then and we still have it), Fontella Bass and Spencer Davis both played the Wheel frequently so would have been played (if only live), Lou Christie (Wheel mid 60s according to the Abardie's website and by Dave Evison in Ms), heard all the Detroit Emeralds tracks played at some time myself (specially their version of Do Me Right at the Unicorn), Backfield in Motion - Wheel. Believe Mr Bloe was played in Ms - certainly Electric Indian's version, bought it because I'd heard it and was collecting instrumentals at the time.
As for the Showstoppers well... It was SO big over here when first released that it got reissued in the states being promoted as the big Mod sound in the UK, following a brief flush of fashionable interest in mods in New York after an article about them in US Vogue (65 from memory).
Dx