Yes it is a Svensson's!

I had a go at my first gen.det. today on the Copper Underwing featured in my post of 17th September on:

http://grampybustard.blogspot.com/2011/09/first-night-mothing-for-week.html

All of the external features had suggested a Svensson's rather than the regular Copper Underwing, and this was confirmed by a detailed dissection of the genitalia.  It was a male, and the features clearly matched those in the photos in British and Irish moths: an illustrated guide to selected difficult species (covering the use of genitalia characters and other features) by Townsend, Clifton and Goodey. 

I had a go in preparing a couple of other macromoths just for practice, and can honestly say I am more than pleased with the microscope I purchased.  It is all very well doing these bigger ones, but I can see doing the little jobbies as a bit of a challenge.