Thank you all for your comments. I had a bit of luck, particularly regarding the timing of the hatching. Also, the pictures with the dark background were the result of a happy combination of factors. I needed somewhere sheltered to take the photos, but with lots of natural light, so I took them in the shed with the sun coming through the open door. In order to avoid a cluttered background, I draped a dark sheet over the lawnmower and other bits of assorted gardening equipment and ended up with an unusual result.
I have some Orange-Tip pupa which I have now placed in a secure and sheltered spot on the back garden where they will over-winter. Also, as of last week, a load of Small White eggs which I watched being laid on the wild rocket plants I was growing in a pot outside the back door. I will be monitoring the development of both species and posting photos in due course.
Vince
EDIT 2014
A fuller report can now be found here:
viewtopic.php?t=7520&start=10000
