The London Festival Symphony Orchestra

Appears as classical music orchestra conducted by Thomas Greene on releases of Collection Richesse Classique series.

It was never confirmed that those artists (orchestra and conductor) exist indeed.
There are very likely pseudonyms for fraudulent reasons. That was usual practice of Philippe Thomas (producer of those releases and founder of Musidisc-Europe) according to first hand testimonial of Pierre Jaubert.

It looks like those releases issued under Thomas Greene and The London Festival Symphony Orchestra names were indeed previously issued on other labels under other names. It has been suggested that:
. [url=https://www.discogs.com/Rimsky-KorsakovLondon-Festival-Symphony-Orchestra-Thomas-Greene-Sch%C3%A9h%C3%A9razade-Suite-Symphonique-Opu/master/867860]Rimsky-Korsakov Schéhérazade[/url] could be [url=https://www.discogs.com/Rimsky-Korsakov-Sir-Eugene-GoossensLondon-Symphony-Orchestra-Scheherazade-Symphonic-Suite-After-The-/master/695952]LSO / Eugene Goossens on Everest[/url]
. [url=https://www.discogs.com/Anton-Dvorak-The-London-Festival-Symphony-Orchestra-Thomas-Greene-Symphonie-N5-Du-Nouveau-Monde/master/1211159]Dvorak New World Symphony[/url] could be [url=https://www.discogs.com/Dvorak-Leopold-Ludwig-Conducting-The-London-Symphony-Orchestra-New-World-Symphony/master/371680]LSO / Leopold Ludwig on Everest[/url]
. conductor on [url=https://www.discogs.com/Edvard-Grieg-Ronald-Smith-4-Thomas-GreeneLondon-Festival-Symphony-Orchestra-Concerto-Pour-Piano-Et-O/master/1037353]Grieg Piano Concerto and Peer Gynt Suites[/url] could be George Weldon

Plus, 4 Chefs-D'œuvre has a mention of Oriole Records Limited and Embassy licenses, but 4 Chefs-d’œuvre has no more those license mentions as the 3 other versions (4 Chefs-d'œuvre, 4 Chefs-d'œuvre, 4 Chefs-d'œuvre) with same cat# which have Thomas Greene and The London Festival Symphony Orchestra instead of Michael Freedman and The London Metropolis Symphony Orchestra on the 2 other versions.