In 1891 he was living with his parents, sister and 12 servants at Platts Lodge, Werneth Park, Oldham:
Samuel Platt, 45, Head, Mechanical Engineer, born Oldham
Helen Platt, 28, Wife, Ireland
Alice Platt, 5, Daughter, Oldham
John Platt, 0, Son, Oldham
Eliza Grainger, 41,House Keeper, Southwick, Sussex
Emma Clarke, 28, Housemaid, Chester
Lizzie Hiden, 23, Housemaid, Evesham, Worcestershire
Ellen Banks, 22, Kitchen Maid, Ashburton, Herefordshire
Emma Heath, 21, Housemaid, Clifton, Staffordshire
Ella Wargent, 18, Scullery Maid, Newtown, Herefordshire
Ellen Smith, 16, Laundry Maid, Clifton On Teme, Worcestershire
Edith Swann, 21, Housemaid, Middlesex, London
Mary Northover, 17, Nurse Maid, Warminster, Wiltshire
Frank Elwis, 25, Footman, Finningley, Nottinghamshire
Ellen Johnstone, 27, Ladies Maid, Berwick On Tweed, Northumberland
Mary Colling, 23, Nurse, Tavistock, Devonshire
In 1901 aged 10 he was a boarder at Manor House School, in Cheam, Epsom, Surrey.
In 1902 on the 5th September, his father, Samuel Radcliffe Platt who was the head of Platt Bros a large Textile Machine Company in Oldham, died aged 52.
From April 1904 until July 1909, he was at Eton in Mr. Tatham’s house. Although he won none of the major subject prizes, he consistently won prizes for his performance in Trials (end of term exams) and holiday tasks, as well as getting three distinctions in Trials. He ended up as Captain of the Oppidans, the senior non-Scholar in the school, and was a member of the Eton Society (Pop).
In 1911 he was at Oxford University and his mother and sister were living at Youlston Park (23 rooms), Shirwell, Barnstaple, Devonshire:
Helen May Platt, Head, 48, Private Means, born Carrigaline Cork
John Rookhurst Platt, Son, 20, Oxford Undergraduate, born Oldham
Nancy Quinelda Platt, Daughter, 15, School, born Chester Cheshire
Evelyn Radcliffe, Sister, 52, Carrigaline Cork
Frank Vivian Radcliffe, Nephew, 25, Land Agent, Oldham Lancs
Theodore Michael Roberts, Visitor, 57, Examiner To Civil Service Commission and Co, born Dublin
Mathilde Lemhardt, Governess, 38, Stuttgart, Nationality German
Ellen Wherton, 42, Housemaid, Clay Cross Derbyshire
Emma Ellston, 27, Housemaid, Halwill N Devon
Edith Bale, 17, Housemaid, Bratton Fleming Devon
Edith Mounty, 17, Kitchen Maid, Witham Ricing Somersetshire
Albert Smith, 15, Scullery Boy, Barnstaple N Devon
Ernest Lewis, 15, Pantry Boy, Newport Wales
Ellen Ackroyd, 26, Ladies Maid, Enfield Middlesex
Sarah Gregory, 48, Ladies Maid, Stoke Staffordshire
William Worth, 18, Garden Boy, East Down Devon
Florence Callaghan, 24, Parlour Maid, Clobelly N Devon
In the First World War he was a Lieutenant in the Royal Field Artillery, 3rd (Northumbrian) Bde, and was killed in action on 27 March 1916 by shell fire on Hill 60, near Ypres, aged 25.
He is buried at Railway Dugouts Burial Ground, Belgium. Grave Ref: III. E. 13.
Probate record:
Platt, John Rookhurst of Youlston Park near Barnstaple, Devonshire died 27 March 1916 in Belgium from wounds received in action. Probate London 16 June to Joseph Platt Hall electrical engineer, Samuel Roberts Radcliffe major His Majesty's Army and Eric George Claydon solicitor. Effects £234559 8s. 3d.
Photo from
http://www.iwm.org.uk/collections/item/object/205387204 
