When I came back to my desk after a break this morning I caught sight of the reflection in my reading glasses of the light coming in the window through the Venetian blinds. So of course, I had to take another break straight away so that I could take some photos!
The results aren't quite what I had in my mind's eye, but that's often the way, isn't it? I can always come back to this subject again some time and give it another go.
I did all the processing in Aperture. The colour effect is a result of using a cross processing preset on top of what Aperture calls 'colour monochrome'