Sorry, Bill – I reject this explanation out of hand! I have eaten this dish and different forms of it for many moons and it has NEVER had ANYTHING to do with rabbit – that might be said to be the whole point! This is a more typical recipe:

http://chantry.ir.ucf.edu/~kat/recipe/Welsh_Rabbit

For a quick YART try the Coming to you first thread under W&F. Do me a favour and post the link if anyone finds this - trawling thru' the archives gets more and more difficult when you have only the 'last accessed' indexing to assist!