Francis should be found on the 1881 census, which will show his parents hopefully, as he was born:-
Births Jun 1880   
 
STARTUP  Francis Cecil H    Kensington  1a 149 
Murphy rules - Father isnt there, and Mum is not shown as Head, altho' they have their own Schedule #, they seem to be in the Household of a George Handley (a Carpenter).
RG11; Piece: 24; Folio: 16; Page: 27 Kensington: 71, Abingdon Villas
 
Ann Startup 34 Wife Married born Sussex, Petworth
Francis Cecil Startup 11 months old  born Kensington