there is a medal card for a William W Fidgeon on the National Archives site,,,,but these only give basic details,,,name,number,regiment and medals awarded,,so no way of knowing if hes yours,,,but cant be many ww fidgeons around ? 
Description:
Medal card of Fidgeon, William W
Hertfordshire Regiment
10302
Private
Bedfordshire and Hertfordshire Regiment
270204
Private
I've just looked these up - very helpful thank you.
I'm thinking the william w must be him because as you say there probably wouldn't be another one.
If they lived in Essex do you think they could be fighting for hertfordshire regiment?
I think I've also found Thomas:
Medal card of Fidgeon, Thomas
Corps
Regiment No
Rank
Machine Gun Corps
3216
Private
Royal Fusiliers
4938
Private
And my great grandfather:
Medal card of Fidgeon, Harry
Corps
Regiment No
Rank
Royal Garrison Artillery
24785
Corporal
Royal Garrison Artillery
24785
Serjeant
If I went down to the national archives at KEW do you think I could view these personally?