Sorry to interrupt the current thread but this looks like the clincher. Rough translation from
[Pionnair-GE]
01.07.1920 The first flight Paris-Geneva subsidised by the Air Ministry. From Le Bourget, Sopwith 130HP three-seater with passengers in 2 hrs 55min. 1st International air service to Switzerland.
The French register in aviafrance.com lists F-CMAP as a Sopwith Triplace.
The picture looks like le Bourget.
And, if it was a significant flight, there is a reason to produce a postcard of it.
So not only a Sopwith but with a date too.
Thanks all, Doug