Hello,
I have a conversion table to convert BSS (BS 2782) to Shore A (15 sec, ASTM 2240-68) which I picked up at a trade fair from the stall of a company called PORTEX LIMITED, which is a major PVC converter in England. I am sure they have an internet address, so you can contact them. If not, give me your Fax-No and I can fax the table to you.