Finding a photo of a WW1 soldier

[celt11]

I am looking for David Rodger or Rodgers if I am not mistaken my first cousin 3 times removed .He died in Salonika in ww1 and is on the PortGlasgow war memorial .
https://www.inverclydeww1.org/honour-roll/david-rodger

[Andy J2022]

It's worth remembering the type of photography which was in use during the First World War. Most of it was a fairly technical process which meant it was done by professional photographers in fixed or temporay studios. We don't get many of the type of relaxed group shots taken by amateurs with their Box Brownies which were so common in World War Two.
Therefore you are looking for a portrait which the soldier or his family had specially commissioned and which was intended primarily for his family, and possibly some close friends. Photographs of individuals (or at least named identifiable individuals) were not taken by the official war photographers covering the fighting.  So while it is just possible that you will find a captioned photograph of David Rodger in a museum (you could try the Argylls or IWM for instance), I would say the odds are very low.
You need to look within the family which is where any portrait of him would have ended up. Often the problem is that such photographs don't have the person's details recorded on them because at the time everyone who needed to, knew who the person was. Old photographs of this type do turn up in car boot sales or flea markets, or even eBay, but are rarely identifiable.