Hi Bruno,
The rounded front on the forward section of the rudder balance, the deep fuselage which possibly has a very small head rest, the grey, flat fuselage sides (the grey finishes at the lower wing trailing edge), and the fact that it's a double bay biplane which looks unmistakably like a Sopwith tells me that this is a Sopwith Salamander. It is evident that the lower wings are fitted with ailerons, which the Salamander and many other Sopwith designs have.
That is a very nice photo, thank you Bruno!