I can't view the Ancestry record. Is it the same as this one?
1871 Living at Caledonian Crescent, St James Clerkenwell, Holborn, London & Middlesex
Samuel and Louise Nash with children Ellen J, Henry S, Herbert, Louisa and William W. All children born in Middlesex.
Registration district Holborn
Piece number 391
Folio 8
Page 10
There is a marriage in MQ 1876 Pancras 1b 127 of a John Edmund Stamp to a Louisa Nash.
However further investigation shows it can't be this family as the Louisa born in 1868 is still there in the 1891 census.
Perhaps you can give me details of the 1871 census so that I can find the one you have. Head of household's name, birth year and place of birth should do.