James,
You are welcome, but I thought that the next question would have been “what is your source”. The answer would be “I have read the file”.
Regarding the Celtic Boss, the original idea was to include all three of the national colours, but with war approaching it was decided to reduce the visibility by dropping the white segment. Later a white square background was included with the fuselage boss at the request of the army units to avoid confusion with RAF aircraft operating over and around Ireland at that time. This lasted up to and including the purchase of the Seafires in 1947. New aircraft purchases reverted to the two colour boss and lasted until mid 1956 as listed in the previous posting.HTH.
Tony K.