I need help finding a family in the 1881 census, please.

I have James and Fanny Luscombe in North Tamerton, Cornwall in 1871 (RG10 Piece 2213, Folio 7, Page 3) and but can't find them in 1881. I'm really trying to locate their son (Arthur James Luscombe) born in 1876 in Deptford. I've found him in Lewisham in 1891 (RG12, Page 522, Folio 167, Page 9) but no luck with 1881.

I've searched North Tamerton District 3 and District 4 page by page but they don't seem to be there so I presume they had departed to London somewhere?

Thanks for any help.

AudreyF