There is another picture of the piece on the site that you will want to check out. I recognize this style from another draftsman for a piece that was up for auction a few years ago and will have to go digging to put them together in my big map of caskets.
This one was sold at Christies in 2006 and was certainly drawn by the same hand. The front panel is almost identical with who may be Jesus being wrapped and prepared for burial? Note that one has a unicorn on the end and the other doesn't. There is another piece and I am struggling to find it in my files and I have to get to other stuff now... think I wasted a few hours looking for it already!