The aftermarket/pattern Redditch dual seats are not very good in some respects, unfortuately.
All the examples I have had from Hitchcocks' sit too low at the front if you use Hitchcocks' front brackets without a 1" spacer between the bracket and the seat base each side, which is what has happened with the Fury in B.W.'s photo. Either the brackets are wrong or more likely the seat manufacturer has made the base's sides too deep. It also means the back of the seat points too high unless you are inclined (no pun intended) to lower the rear bracket.
The second glaring problem is that the seat in the first two pictures is just too long at the back by about two or three inches, hence the ugly overhang.
A quick look at the originals in Malky's post confirms that they were both shallower and shorter at the back.
I think the bike in question is presently on the wrong side of the Atlantic for us foreign guests, but I hope it eventually goes to someone on this forum.
A.