One of the flyers that came with my Schiffers book on ACW revolvers is entitled as above. It mentions the "enigmatic 'Battle of Britain' models.
I googled the term. Seems that when the Brits were desperate for arms in WWII, Colt responded with a shipment of the SAA's models they had on hand - 36 chambered in .38 Spl., 19 in .357 and 108 in .45 Colt.
To say that these revolvers are rare and worth their weight in gold is an understatement.