I am in the process of building a Bolt Action 28mm Home Guard force, I did want to add some armour to them with a Mark IV Male World War One tank put into service, even if it was merely as a mobile pillbox.
The Bovington Tank Museum has on display a Mark IV Male tank that was used just in this way. It was used in World War One and then presented to the Navy. When war broke out in September 1939, the Tank Mark IV (Male) number 2324 was refurbished for Home Guard duties.
Having constructed and undercoated the Mark IV Tank the next stage was a base coat of Army Green Spray from the Army Painter range. I then used a Humbrol Tank Grey 67 spray for the dark colour camouflage pattern. For the tracks I used Citadel Gorthor Brown.
I then gave the model a wash using Citadel Seraphim Sepia Shade.
I did one side at a time to try and stop the shade pooling too much.
I am aiming to use some more shades across various parts of the model.