Hi Facellia,
Possible

1881 Census
65 Seaton St
St Lukes, London
RG11/75/18/30
Arthur HERRIOTT, head, mar, Police Constable, Street, Sussex
Harriet Herriott, wife, mar, born Sussex, Storrington
William COOPER, 25, brother in law, unm, Drayman, Sussex, Storrington
ARTHUR GREEN, 4, nephew, scholar, born Sussex, Patching
Marriage;
Harriett COOPER
Arthur HERRIOTT
December 1875, Chelsea, 1a 488
Now to summarise Arthur is either Harrietts or Arthurs nephew.
Going from what you said about Arthurs parents being John/Maria, there is this marriage;
John GREEN
June 1876
E. Preston
2b 531
On same page Maria COOPER
If this is correct there are 2 possible births in East Preston, 1 in 1875 and the other 1876.
Did Arthur have a second name on marriage cert?
Trish