Hello Dominic
That sounds really fascinating.
Col. Griffith is Charles Matthew Griffith (1834-1913) - he saw action in the Afghan war at Ghirisk, Maiwand and Kandahar.
Frank Whittuck I know because I researched him for my database.
Here's his entry.
Mainwaring is also a name I recognise from my researches into the southern Afghan theatre, and he is most likely Col. William George Mainwaring (1823-1905) of the 30th BoNI.
I won't tackle the place names just yet as it would help to know which places are mentioned before and after to try and help locate the rough area.
The southern theatre of the Afghan war is something I'm quite interested in and have been collecting resources on for a while, so do feel free to
email me if you think I can help further.
All best -
Garen