There is a David Sabiston age 20 listed in the 1851 census at Graemsay
1851, Graemsay, District: 4, Property No: 43 - South Clates
1,Hugh,Lyon,Head,Mar,M,34,Fisherman,Graemsay
2,Isabella,Lyon,Wife,Mar,F,29,,Graemsay
3,Hugh,Lyon,Son,,M,1,,Graemsay
4,David,Sabiston,Visitor,S,M,20,Shoemaker,Rendall
Gorseness is in Rendall so this would fit.
Orkney Family History Society is an excellent source of information
www.orkneyfhs.co.uk