Having used a mixture of polyfilla (wall filler), white glue, brown paint, model railway ballast, model railway coal and some water I added the mixture to the board.
Once this was dry, I spray painted the board.
I first used black spray, then a dark earth and finally a grey spray.
I now have to dry brush the terrain.
Due to a few gaps in the terrain I will be making this a green landscape with lots of foilage.