Thank you for your continuing suggestions. In the 1841 census, George is in South Elmham, Suffolk, and the entry in the "Whether born in same County" column is 'N'. In the 1851 census, George's birthplace is stated as "uk" (which I take to be short for 'unknown'), which isn't very helpful at all. His siblings are all born in South Elmham, Suffolk, the first sibling being baptised in April 1823. Samuel's occupation was Agricultural Labourer. It is possible that Samuel had to seek work far away from Suffolk, although I must admit that Sussex is quite a distance to travel!
By the way, in the 1881 census, it is clearly written Sussex in the "Where Born" column.