Well Eileen
Here goes with the information you provided. It would have been ideal to see if the writing on the back of the photo was written by the same person and particularly written in a continental-style hand.
Still, I hope that this is your couple, as this man died on the date provided and at Valliere (St-Valery-en-Caux). The Highland Division surrendered after their 60 mile fighting retreat that enabled the BEF and the French army to be evacuated at Dunkirk. The date of surrender was the 12th June, 1940 - how sad, as your man died the day before that.
Having checked the records and with your information, there was only one Gordon Highlander officer killed that day (and none the previous days before). So I am fairly sure this is the family:
Name: COLVILLE, FREDERICK JAMES
Initials: F J
Nationality: United Kingdom
Rank: Captain
Regiment/Service: Gordon Highlanders
Unit Text: 1st Bn.
Age: 27
Date of Death: 11/06/1940
Service No: 50797
Additional information: Son of Admiral the Hon. Sir Stanley Colville, G.C.B., G.C.M.G., G.C.V.O., and of Lady Adelaide Colville (nee Meade), of Crawley Down, Sussex; husband of Dorothy Loisa Colville, of Paddington, London.
Casualty Type: Commonwealth War Dead
Grave/Memorial Reference: C, 7.
Cemetery: ST. VALERY-EN-CAUX FRANCO-BRITISH CEMETERY
