It is perhaps worthy of note that all the western allies carried tricolor rudder flashes, UK, France, Belgium, Italy and the USA, so there must be a nod to convention somewhere.

John

Further to me posting this I have in my book collection, Owen Thetford’s own copy of Camouflage ’14-’18 Aircraft ( a very slim A5 size volume) and in this he quotes “On Dec 11th 1914 an official order to the effect that all British aeroplanes were to carry Red, White and Blue cockades on the wings with a small Union Jack under the tips. The Union Jacks were dispensed with in early 1915. The tri-colour vertical rudder markings were introduced in May 1915 in the manner of the French.

John