If your grandparents are the Sara(h) Heller and Joseph Cantor who married in Poplar in 1929 then a bit of research will probably reveal lots of living relatives...
Groom: CANTOR, Joseph
Bride: HELLER, Sarah
Registration district: Poplar
County: London
Year of registration: 1929
Quarter of registration: Oct-Nov-Dec
Volume no: 1C
Page no: 890
This may be Joseph at home with parents and siblings in the English 1911 Census
CANTOR, Isaac Head Married M 43 1868 Wood Carver Russia Resident
CANTOR, Sarah Wife Married20 years F 44 1867 Russia Resident
CANTOR, Abraham Son Single M 19 1892 Wood Carver London Bethnal Green
CANTOR, Florence Daughter Single F 17 1894 Shorthand Typist London Bethnal Green
CANTOR, Priscilla Daughter F 13 1898 School London Bethnal Green
CANTOR, Harris Son M 11 1900 School London Bethnal Green
CANTOR, Joseph Son M 5 1906 School London Bethnal Green
RG number: RG14 Piece: 1146 Reference: RG14PN1146 RG78PN38 RD11 SD5 ED7 SN137
Registration District: Hackney Sub District: South East Hackney Enumeration District: 7
Parish: St John At Hackney Address: 5 Shore Road S Hackney NE County: London
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