Definitely 207 Sqn as you say Paul - there's a photo in the Air Britain D.H.4/D.H.9 File of E726 of 207 Sqn with the same style nose number, this one...
Many thanks indeed Ross, and yes the ORB is for April 1st 1943. Apologies - been staring at badly-scanned ORB files on the National Archives website...