Disclaimer: I am one of the original DMA Design guys - I'm one of the faces in the Lemmings end screen. I kind of doubt the "drunk old dude" story in Edinburgh was real, none of the guys who developed the game were remotely like that and I'm pretty sure the animator was teatotal. I've even had an experience where some stranger in a pub told *me* that he created Lemmings. Sure.
I remember when the "Satanic" letter came around, purely because the level was built in the shape of "666". Further irony, the level designer on that one - Mike Dailly, who happened to create Lemmings in the first place - is rather more devout than many.
Anyway, Mike's DMA history site is at www.dmadesign.org and my own DMA site (newer and not as much there at the moment) is at www.dmadesign.net