|The finished painting|
Geoff encouraged us toward a looser style and the omission of too much detail.
Two things particularly impressed me with the demonstration were:  the use of a very limited palette (I think he used only Ultramarine, Burnt Sienna and Raw Umber);  the light that seems to shine out of this picture.
Geoff had done his drawing in advance and had applied masking fluid to the trunks of the foreground birches. The images that follow show the progress of the painting.