The MGA register web site lists the color as Old English White. They don't give a paint code, but the MGB OEW is listed in this web site
http://www.teglerizer.com/mgcolors/index.html along with a paint code. I would expect it to be very close if not the same as the MGA color as the same code is also listed for Midgets that were produced at the same time the MGAs were being built.
'73 Midget (V6)
'59 MGA (I6) under construction
'73 Lotus Europa
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