Killed in action aged 26
No known grave.

Cornwallis John was born at Highams, Woodford Green, Essex, the son of Colonel Sir Thomas Courteney Theydon Warner, 1st Bt, CB MP formerly Lt Colonel and Hon Colonel commanding 3rd Oxfordshire and Buckinghamshire Light Infantry, Lord Lieutenant in the County of Suffolk, and Lady Leucha Diana née Maude sixth daughter of Cornwallis 1st Earl of Montalt.

Educated at Eton and Christ Church he was called to the Bar in 1910, and in December of that year unsuccessfully contested Salisbury as a Liberal candidate.

He joined 3rd Oxfordshire and Buckinghamshire Light Infantry as 2nd Lieutenant 25 July 1906, and was promoted Lieutenant on 5 March 1910.  He resigned in May 1914, but rejoined 26 September following.

He went to France on 26 December 1914 where he was attached to 2nd Battalion of his Regiment and was killed in action at Richebourg L’Avoué on 16th May 1915. His Commanding Officer wrote “I cannot say how I miss your son. He did such excellent work last spring that if he had been spared at Richebourg as far as I am concerned he would have commanded a company here ever since. There are a thousand and one jobs I would have given him to do. He was such a very useful and reliable officer in so many ways.“

His name is on the Le Touret Memorial Panel 26.

From the London Gazette dated the 4th day of February, 1916.
Pursuant to the Statute 22 and 23 Viet., cap. 35.
NOTICE is hereby given, that all persons having any claim against the estate of Cornwallis John Warner, late of 3, Cork-street, in the county of London, a Lieutenant in His Majesty's Army (who died on the 16th day of May, 1915, and probate of whose Trill was granted at the Principal Probate Registry, on the 2nd day of February, 1916, to Arthur Morris Lloyd, the executor therein named), are required to send in particulars thereof to the undersigned on or before the 25th day of March next, after which date the assets of the; deceased will be distributed by the executor, and regard had only to the claims of which he shall then have had notice.—
STANTON and HUDSON, 108A, Cannon-street,  London, E.C.,
Solicitors for the said Executor.

He left £11,595 17s 0d

There is a memorial to him in the church of St Mary, Thorpe Morieux, Suffolk

“Close by is a bronze tablet for Lieut. Cornwallis John Warner who was killed in 1915;  it has his arms in enamelled colour, with replicas of his four medals and there is a duplicate at Brettenham.”