Hi quiltedlady,
Sorry, I don't have anything substantial to offer. You haven't mentioned which part of London the Bennet Studio is but you could narrow the marriages down by using FreeBMD and each quarter and the London district using the forename Eva. Probably throw up several, if not numerous possibilities, but may be worth it.
Also, you say that you've checked England Army Records - have you tried posting on Forum Military threads? Someone may recognise his insignia and make a breakthrough for you. Have you considered that the groom may not be British? Others will be more knowledgeable, but my husband thinks that the pocket on the trousers doesn't look like a British uniform, and might indicate a foreign force? What about Poland, etc? Worth a thought.
All the best and happy hunting, Kit
Have just seen Pels post. Worth a try eh?
What a handsome couple!