Where did they go?

[Durham Lady]

Sorry if this seems long but I want to give you everything I know.

Richard NORTHEY the 8th child of John NORTHEY and Agness née COX/COCKS was born c1840 in the St Austell District, Cornwall. No birth found in the indexes.

He was baptised at Holy Trinity Church, St Austell 9th August 1840, the family were living at Boscundle.

Richard is with his parents in 1841
Tregrehan Mills HO7/146 Folio 17 pg 26

1851 Family listed as NORTHY
Charlestown HO107; Piece: 1907; Folio: 86; Page: 7

1861 Richard is with his widowed mother in Tavistock,Devon, she was born there.
RG9; Piece: 1462; Folio: 68; Page: 27

On 15th September 1864 a Richard Cox NORTHEY a miner son of John NORTHEY married an Eliza Ann THOMAS daughter of William THOMAS a mariner at St Paul's Church, Charlestown, Cornwall
Witnesses were Thomas HARRIS and George NORTHEY

Richard has a younger brother George and one of his sisters married a Thomas HARRIS.

My problem is, after the marriage Richard and Eliza seem to disappear.

I've tried census in Wales, Scotland, Isle of Man, Channel Islands as well immigration/Emigration but nothing seems to be coming up for them.

Has anyone any other ideas please?