And don't forget the Vickers E. F. B. 4 which came after the 3. This is the way I wrote it up in my upcoming book:
After the Admiralty ordered Vickers to build six copies of the E. F. B. 3., Vickers progressed to the new experimental model EFB.4, which featured a more streamlined nacelle, two tail booms, and was fitted with a drum-fed Lewis gun to be mounted on a spigot forward of the gunners cockpit. The single prototype first flew in July, 1914.