This remarkable painting is a self portrait by Laura Knight (1877-1970). I was lucky enough to see the original last weekend in London, at the exhibition of her portraits at the National Portrait Gallery, and very wonderful it was too, as were all her other portraits -- it's on till 13 October so do go if you can.
One of the things that makes this painting so interesting is the fact that she shows herself painting a nude. As this very interesting article in the Telegraph explains, when Knight went to art college this would not have been possible:
While her male classmates were urged to look closely at the nude models in the life-drawing classes, Knight was excluded, left to find out about the body by poring over plaster casts, a disadvantage she believed marred her work for decades.
So certainly this portrait celebrates the freedom she achieved when she moved into a circle of artists in Cornwall. When the painting was first shown in 1913, it was condemned as 'vulgar' and 'regrettable'. Luckily things have moved on a bit since then.