Hi,
If you go to the TNA try and speak to William Spencer who is the best at knowing what military docs are about. He wrote the guide for TNA on medals & WW1 papers etc.
Failing that, use one of the professional researchers from the list TNA will supply, rather than a TNA researcher. a - they know what they're doing and where to take some research & b - a lot cheaper!
Cheers
layerb