Thanks for the thoughts so far, chaps. I instruct out of Dundee and ask the question since I'm doing a lot of night training at the moment and need to be able to tell my students the right thing. The concensus seems to be that you can't go SVFR in class E, only IFR so in this context that simply means staying above MSA (as the transition alt. is 6000ft. and we'd be below that). Does that seem reasonable ? As you can see it's something of a can of worms and I couldn't find an easy answer from the regs.
Cheers DB6