Tabanus: Here's the evidence, a little Q&D:
1876: «Son Mahood» born 8 Sep 1876 at Shore Street, Portaferry Northern Ireland. Father Thomas Mahood, mother: Mahood (Belfast News-Letter, 13 Sep 1876, p. 1) (apparently only Mahood born ca. 1876 with fathers name beginning with T, cf. 1913)
1901 census, St Mary Paddington London (= just S of Hampstead): James Mahood, Boarder, 24, Single, b. in Co. Down Ireland, Govt. Clerk (Paymaster Gents Office); Thomas Mahood, Boarder, 17, b. in Co. Down Ireland, Govt. Clerk (G. P. O.)
1907: marriage 10 April in Folkestone, Kent between James Mahood, 30 and Violet Maud Daintry (England Select Marriages)
1908: James Mahood, 31, of Portaferry, married, living in Cricklewood (= near Hampstead in London), volunteers for 1 year Army service (British Army WWI Service Records 1914-1920)
1911 census, Willesden Middlesex (= also near Hampstead): James Mahood, Head, 34, married 4 years, born in Portaferry. Co. Down Ireland, Civil Servant – Second Division Clerk; Violet Maud Mahood, Wife, 33, married 4 years, born in Paddington London; Kathleen Esther Mahood, Daughter, 3, born in Willesden London; Elizabeth Ann Topsy Pearne (?), Visitor, 50, b. in Marylebone London, Single, Forewoman, Linen Workroom
1913: «He is the younger son of T. Mahood, Portaferry» (chess report in Belfast News-Letter 25 Aug 1913, p. 9)
1950: <MAHOOD James of 16 Regent-road Surbiton Surrey died 14 March 1950 at 30 Teddington-road Teddington Middlesex Administration (with Will) London 9 June to Kathleen Esther Wallace (wife of William Wallace). Effects L5053 7s. 4d.> (probate calendar)