1911 census Isle of Man. Household transcription from Findmypast:

Name, Relation, Condition, Yrs married, S ex, Age, Birth Year, Occupation, Where born:

MCMULLEN, James, Head, Married, M, 34, 1877, Carter, Manchester, Resident [of IOM]
MCMULLEN, Theresa, Wife, Married 2 years, F, 34, 1877, Boarding House Keeper, Isle of Man Douglas
MCMULLEN, Allan, Son, M 1 (1 AND 8 MONTHS) 1910, Isle of Man, Douglas
MCMULLEN, Nora, Daughter, F, 0 (9 MONTHS) 1911, Isle of Man, Douglas
HINTON, Agnes, Niece, Single, F, 18, 1893, Isle of Man Douglas
HINTON, Joseph, Nephew, Single, M, 16, 1895, Isle of Man Douglas.
RG number: RG14
Piece: 34678
Reference: RG14PN34678 RD635 SD3 ED18/25 SN38
Registration District: Isle of Man
Enumeration District: 18/25
Parish: Conchan
Address: 44 Murrays Road Douglas
Isle of Man

1901 census:

MCMULLEN, Jas, Head, Married, M, 51, 1850, Labourer In Coalyard Manchester, Lancashire
MCMULLEN, Margaret Wife Married F 55 1846 Manchester, Lancashire
MCMULLEN, Mary E Daughter Single F 29 1872 Manchester, Lancashire
MCMULLEN, Jas Son Single M 24 1877 Carter In Flour Mill Manchester, Lancashire
MCMULLEN, Eliz Daughter Single F 12 1889 Shirtmaker Manchester, Lancashire
MCMULLEN, Albert Son Single M 18 1883 Carter In Flourmill Manchester, Lancashire
MCMULLEN, Hannah Daughter Single F 13 1888 Box Maker Manchester, Lancashire
Piece: 3707
Folio: 116
Page: 14
Registration District: Chorlton
Civil Parish: South Manchester
Address: 7, Barton Street, South Manchester
County: Lancashire
.....................................

HINTON, Joseph Head Widower M 70 1831 Gardener England
HINTON, Theresa C Daughter Single F 26 1875 Douglas, Isle of Man
HINTON, Agnes Grand Daughter F 8 1893 Douglas, Isle of Man
HINTON, Joseph Grand Son M 6 1895 Douglas, Isle of Man
Piece: 5304
Folio: 82
Page: 7
Registration District: Isle of Man
Civil Parish: Onchan
Address: 42, Lower Murrays Road, Onchan, Douglas
Isle of Man

You could buy the birth cert for Allen who was aged 20 months (1yr + 8) on the night of Sunday 2 April, 1911, which may give more information.
See "Contact" at the top of the page at: www.gov.im/registries/general/civilregistry/

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