Source: Michael Doyle Their Name Liveth For Evermore: The Great War Roll of Honour for Leicestershire and Rutland.
He was the son of John Weston and his wife Alice Elizabeth Weston (nee Everard, married in the 2nd quarter of 1883 in the Leicester district), a teacher and monitoress, born 1854 in Glenfield, Leicester. John Everard Weston was born on the 4th January 1892 in Glenfield, Leics., his siblings were, Margaret Alice, born 1884 and Mary Elizabeth, born 1888, both his siblings were born in Glenfield, Leics., in March 1901 the family home was at Chestnut Road, Glenfield, Leics. In April 1911 John was employed as a chemist’s apprentice and was residing in the family home at 17, Napier Street, Leicester together with his widowed mother and siblings, Margaret, a hosiery trade warehouse forewoman and Mary, a dressmaker. John was employed as a Chemist by the Leicester Public Medical Service, East Bond Street, Leicester from the 4th January 1909 until he enlisted in June 1915. Prior to enlisting into the Royal Flying Corps, John had served as a Corporal 60309 in the Royal Army Medical Corps. Details taken from John’s Royal Flying Corps., record of service show the following:- 1.O.C.W., 27/10/17. Taken of strength, Worcester, 4/1/18. 1. S. of A., Reading, 30/1/18. Temporary 2nd Lieutenant on probation (General List) (London Gazette 19/2/18), 30/1/18. Art. Inf. Sch., 2/3/18. Transferred to the newly formed Royal Air Force, 1/4/18. O.S of A.G., 13/4/18. E.7. 4 Squadron, 25/4/18. Temporary 2nd Lieutenant, Observation Officer (Confirmed) (London Gazette 7210, 18/6/18), 6/6/18. Admitted to 18 Casualty Clearing Station, then 4 Stationary Hospital, 15/6/18. Killed in action, France, 14/7/18.

Source: Leicestershire War Memorials Project.
The following was kindly provided by Richard Chancellor in 2017:

2nd Lt John Everard Weston No4 Squadron Royal Flying Corps. This photograph was taken whilst No4 Squadron were based at St Omer Aerodrome. 2nd Lt John Weston Everard was killed in action along with his pilot 2nd Lt Sydney Moxey whilst taking part in an artillery observation patrol at 7:45am