Only Benjamin Brittain I can find on 1851 Census is born c 1795 Sawbridgeworth, Hertfordshire.
Living in Middlesex.
Benjamin Brittain, 56, Superannuated Policeman
Eliza M Brittain, 52
Rebecca Brittain, 18
Henry B Brittain, 10
Baptised 10 June 1794, Sawbridgeworth to CHARLES/REBECCA Britten**
1861 a Sarah L Brittain, Daug is with them age 24 (1837)
Sarah Louisa Brittain Baptised 7 Sept 1837, St Marylebone Christ Church
Birth 22 March 1836
Rebecca Baptised same day, Birth 10 Nov 1831
To Benjamin/Elizabeth Mary, Fathers Occp Policeman
This appears to be the Family in 1841 without Benjamin;
HO107/654/19/South Mimms
Elizabeth Britto, 42, No born in County
Rebecca Britto, 10, not born in County
Luisa Britto, 5, born In County
William Britto, 6 Mo, born in County