Bangeye, Simpsons is a surplus firearms importer, Simson is a German firearms manufacture from pre WW-II that was Jewish owned and confiscated by the Nazis and renamed BSW. The name was reinstated after the war.
Looking a various German shotguns it looks like Merkel, Simson and Sauer sourced many of there actions from the same place.
Image of JP Sauer action
http://757arms.com/images/product/medium/169_1_.jpgImage of Simson action
http://757arms.com/images/product/medium/106_1_.jpgImage of a Merkel action
http://757arms.com/images/Product/icon/30.jpgSorry I can post a photo but don't know how to pull an image from another site and move it.