664 Sqn at Usworth had brown and green camouflage AOP6s and silver with yellow bands T7s so presumably 666 Sqn’s were the same.
One of the 664 Sqn. AOP6s also carried fighter style squadron markings which were brown and black and, hence, invisible from a distance. It’s possible then that 666 might have had a similar scheme but I’ve never seen anything in print about AOP squadron markings.
Jim