In the couple of hours I had this morning before going away again I managed to get the sky ready for glazing when I return on Friday. It's a particular time of dusk that I am trying to depict and glazing it from now on should give me enough control over how dark I want it to go (not too dark).
Incidentally I normally work on linen but there is no pre-stretched linen available in this size and format so I tried painting two extra coats of oil primer over the Winsor and Newton canvas, fine sanding between coats. This has given me a surface that is nearer to linen and and seems to take the paint pretty much how I want it. I will do this for other paintings from now on as now I know how to change the surface of the canvas.