Teresa - EMI ran several labels in the 60's including Capitol, Liberty, UA, Tamla Motown, Stateside etc.
All of them used a white demo with a red A from approx 1961 onwards.
In very late 1966, early 1967 they decided for some reason to change the demo designs to a green label with a white A.
(A couple changed to pink with silver A)
At the same time, Pye and it's subsidiaries changed their labels from plain white demos with black A's to a yellow demo.
I still don't know why this happened, I'd love someone to tell me, all it appears to coincide with is the end of the pirates and the start of Radio 1.