Thanks for this very interesting info, Colin. I have used your method to check our listed releases of the UK releases of the Ziggy album.
The following posts comply with your method:
IdbD Ref#17046: Titanic/Chrysalis, released 1972
IdbD Ref#17047: Titanic/Chrysalis, released 1972
IdbD Ref#17052: MainMan/Chrysalis/Bowie, released 1981
IdbD Ref#17053: MainMan/Chrysalis/Bowie, released 1980
IdbD Ref#26754: MainMan/Chrysalis/Bowie, released 1980
The following posts apparently don't comply:
IdbD Ref#17048: MainMan/Chrysalis, listed as released 1972, should be 1974/5?
IdbD Ref#17049: MainMan/Chrysalis, listed as released 1972, should be 1974/5? *
IdbD Ref#31512: MainMan/Chrysalis, listed as released 1972, should be 1974/5?
The following don't have an accurate release year:
IdbD Ref#17050 has MainMan/Chrysalis credits, indicating 1974/5 using your mehod *
IdbD Ref#17051 has MainMan/Chrysalis credits, indicating 1974/5 using your mehod, but black labels were not introduced that early, as far as I know *#
IdbD Ref#17568 has MainMan/Chrysalis credits, indicating 1974/5 using your mehod *
* This release also has a MainMan logo, which indicates it was released later than 1972 (cf. your post
IdbD Ref#32713)
# Could it be that RCA simply re-printed the earlier orange labels, without changing the publishing credits (nor anything else on the labels), when the black labels were introduced around 1980 (possibly 1979)? In that case the method does not work for black labels.