Both he and his brother used the last names Nagel, Nagle and Eastman-Nagle

India Select Births and Baptisms
Ernest Rudolf Dudley Nagel born September 12, 1896, Bengal, India, baptism October 4 1896, Kashmir, Bengal, India, father Rudolf Nagel, mother Katherine Hannah Elia

In the 1901 census 75 Richmond Road, Shirley, Hampshire
Head Rudolph Nagel, age 41, clerk in Holy Orders Church of England, born Austria, foreign subject of Austria.
Wife Katherine H. Nagel, age 36, born Bengal, India.
Son James N. Nagel, age 9, born Darjeeling, India
Son Ernest R. D. Nagel, age 4, born Cashmere, India
Daughter Isabel K. Nagel, age 1, born Freemantle, Hampshire
2 boarders, 2 servants

UK British Army Lists 1918
Ernest R. D. Nagel, born September 12 1896, 2nd Lieutenant, Royal Artillery.

UK WWI Roll of War Service
University of London, Officers Training Corps
2nd Lieutenant (Temporary Lieutenant) Ernest Rudolf Dudley Nagel, Royal Field Artillery, St. Thomas’s Hospital

University of London Student Records War List
Ernest Rudolf Dudley Nagel (St. Thomas’s Hospital); Lieutenant Royal Field Artillery, attached Royal Flying Corps (wounded)

UK Outward Passenger lists
Departed Bristol, England on the Patuca, July 17 1919, destination Kingston, Jamaica
Ernest Rudolf Dudley Nagel, 1st class, medical student, country of intended future residence England

UK Incoming Passenger Lists
Departed New York, New York, United Stated, arrived Southampton, England, October 14 1919, on the Lapland
Ernest R. D. Nagel, age 23, student, St. Thomas Hospital London SE1

UK and Ireland Outward Passenger Lists
Departed January 20, 1925, London, England on the Lautaro, destination Lobitos
Ernest

New Orleans Passenger Lists
Departed Cristobal, Canal Zone on the Granada, arrived January 20 1927
Maud Eastman-Nagle, age 34 years 2 months, married, housewife, able to read English, French, Spanish and Italian, British nationality, born Portsmouth, England, Visa issued at Lima, Peru, April 17 1926, last permanent residence Lobitos, Peru
Earnest Rudolf Eastman-Nagle, age 30 years 4 months, married, surgeon, can read English, Spanish, French and German, British nationality, born Srinagar, India, visa issued at Colon R.P. January 10 1927, last permanent residence, Lobitos, saloon class
Ernest Eastman-Nagle, last address in UK 27 Bryanston Street London W1, surgeon, age 28, country of last permanent residence England, country of future permanent residence Peru
Maud Eastman-Nagle, age 32

US Border Crossings
Detroit Michigan, June 3 1930
Ernest Rudolf Dudley Nagle (Nagel)
age 33 years 8 months, single, physician, born Srinagar Kashmir India
Nationality India, Race Magyar, language English, money shown $200
last permanent Residence Toronto, Canada, destination New York, New York
ever in US November 19 1907 to October 19 1909, where Kansas and Massachusetts
Going to Boarding House 116 W 45th Street New York City
purpose in coming and time remaining in US Dom? perm (permanent?)
height 5’ 10”, complexion medium, hair medium brown, eyes blue
Name and address of nearest relative or friend in country whence alien came, Brother James Nagle, Calcutta, India
Place of Issue Toronto, Canada
date of landing November 1927, Mobile Alabama on the S.S. Tela

The Medical Directory 1935 and 1942
Ernest Rudolf Dudley Eastman-Nagle, c/o R. Section, Lloyds Bank, 6, Pall Mall, SW1 - Member of the Royal College of Surgeons England, Licentiate Royal College of Physicians London 1921; Licentiate in Medicine and Surgery of the Society of Apothecaries London 1920; (St. Thomas); late Cas Surgical Officer St. George Hospital; House Surgeon Seaman’s Hospital Greenwich; Field Medical Officer Lobitos Oilfields, Peru.

London Electoral Registers 1936
183 Lancaster Road, Kensington
Ernest Rudolf Dudley Eastman-Nagle
Maud Eastman-Nagle

In the July to September 1939 marriage index Ernest R. D. Eastman-Nagle and Maude Hodge, Paddington, London, Volume 1a, page 206.