Today I managed to fit in an hour or two of painting and this is the result. I under painted the Sardinia Cove initial sketch with a pale mauve sky and then I painted the sea with a darker mix of the same by adding cerulean blue to the initial mix of permanent mauve and titanium white. The land surrounding is darker still by just intensifying the cerulean and mauve levels in the mix and so this is the finished underpainting. This is a bit of an experimentation. The aim is to give the final painting colours more resonance from the effect of the under colour interaction with the top layers.
Below is the first layout of the sketch on canvas.