Thank you Frances, that's very interesting. This Samuel must be a brother of Welles. I checked the IGI and there is a Samuel Herrick Surplice born in 1802 in Beeston, Notts who is probably father to both of these men. Welles was also born in Beeston.
Apart from Welles Surplice's family, there were no other Surplices on the island on the 1881 census so Samuel must have moved to the island just before he died. It's all so fascinating.