Di,
Are they the family in Fulford, Yorkshire in 1841? Mary, 35, with children Mary, Elizabeth, Joshua and Ann.
If so, could this be Mary in 1851 living with a Moule relation? There is a discrepancy in birthplaces between Norwich (as per IGI) and here, where it's noted Scotland though.
Address: 18 Hill Street, Knightsbridge, MiddlesexJemima E. Moule, head, unm., 60, proprietor of houses, b. London
Mary Moule, niece, unm., 18, -, b. ScotlandEmily Jordan, serv., unm., 26, gen. serv., b. Painswick, Gloucestershire
hume