I found that B & Q do a nice range of fluorescent fittings with electronic ballast that are also very compact. They also conveniently trap all the light coming out of the 'back'. I aim to make sure that only the light that is necessary shows, all the other light is, as far as possible, stopped. These fittings will take the tubes that we really want to use.
and here is an inside view of the bottom part. The added reflector needed to balance the light output is also there - a short version just used for testing. Once the reflector was adjusted, total variation in illumination was less than 1 stop, and with no sudden changes had a very smooth and regular appearance.We did a view test with this version which gave very good results, although some prints seemed to benefit more from this lightbox than others, at this stage we could see no obvious reason for this.