Having found my 4x great-grandfather Henry GASSON in the 1861 census and confirmed that he didn’t die in 1860 there is only really one other likely death registration in the GRO indexes. This one is in Q4 1862 and like the 1860 one it is in the Horsham Registration District, so everything seems to fit quite nicely.
There is a burial entry in Slaugham (according to the SFHG Data Archive) in December 1862 for a 78 year old Henry GASTON which is quite possibly my Henry. The dominant spelling of the surname was GASSON around this time, but variations such as GASTON are still to be found from time to time.
There is only one thing that isn’t quite right and that is the fact that the burial register records Henry as coming from Beeding. This probably isn’t a problem because Lower Beeding is a couple of miles west of Slaugham, so it is quite possible that Henry was living nearby (there were certainly other GASSONs in Lower Beeding at the time) and was brought back to Slaugham to be buried with his wife.
I still need to check the burial entry against the original register (or at least a microfilm of the original) but I am pretty confident that this is my Henry GASSON. Confident enough to put my money where my mouth is and get out my wallet and order the death certificate. I might even splash out and order the one for his wife Catherine at the same time.