I've started adding detail to the gravestones and the drystone wall here, which is helping to create an extra feeling of three dimensionality. I am a bit worried that it's still looking very dark, so I might start adding brighter colours here.
The version on the right shows a lighter background for the hills behind the church which I am now unhappy with and will put it back to the version on the left which is more of a silhouette, rather than the strangely lit version on the right. I've also gone back to the brighter version for the building as the previous stage was looking too muddy. Looking at Piper's paintings the colours were always quite clear, so I will go back to my original idea of scumbling darker paint over the dry underpaint, which means just waiting for the paint to dry.