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 being B3.
Could the last three be 101? Can't see anything that matches either 401 or 101 in the book though.
Maybe there's something in the AB 207 Squadron book 'Always Prepared'?
Regards
Simon
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