I've posted the pic again here for clarity. It's clearly an advanced military machine and not an early flying boat/seaplane. It's got a wheeled undercarriage! The boy in the rear observers position has his elbow on a circular machine gun rail!
As well as the military paint job, please notice the military RFC roundel on the fuselage! These were applied from the very beginning of 1915, This modified roundel on this aircraft with the thin white outline came into use in 1917. This photo can not therefore be from before that date!
The aircraft itself is an Airco D.H.9a. The prototype flew in march 1918 and production got into swing shortly after that. This photo can not therefore be from before mid 1918. Link here
[size=78%]https://en.wikipedia.org/wiki/Airco_DH.9A[/size]There is a white letter "H" on the rear empennage. This shows it is in the end block of D.H.9a production which continued over into 1919. The photo must therefore be no earlier than mid 1918, but could be 1919.
Wells Aviation ceased in being in 1917. They did not get to build any D.H.9a aircraft, so it's clearly not one of their builds. Please note it is in a military style aviation hanger, not a pottery or converted house in Chelsea.
Below is both your image and another D.H.9a for comparison.
There's something else in this photo that makes it evidently not the seaplane from Well's story. Any guesses anyone?