Cather was born in Streatham Hill, south-west London, on 11 October 1890 to R. G. Cather, who worked for the tea merchant company Joseph Tetley & Co., and his wife Margaret. His mother was the sister of the politician David Graham Shillington. He was educated at Hazelwood School in Limpsfield before going onto Rugby School. His schooling was curtailed in his mid-teens by the death of his father. He went to work for his late father's company, Joseph Tetley & Co. He spent much of the period from 1911 to 1914 in the United States and Canada on business.
On 3 September 1914, Cather enlisted in the British Army's Artists Rifles. He already had some military experience, having served for two years in the Territorial Force with the 19thRoyal Fusiliers from 1909 to early 1911. The following May, he requested a transfer to the Royal Irish Fusiliers on account of his parents both being from Northern Ireland. He was accordingly granted a commission in the 9th Battalion, Royal Irish Fusiliers, which was part of the 36th Division. Sent to the French sector of the Western Front in October 1915, Cather was soon promoted to lieutenant and became adjutant of the battalion. The following July, the 36th Division took part in the Battle of the Somme. On 1 July 1916, the opening day of the battle, Cather's battalion was tasked with capturing Beaucourt Station, near Beaumont-Hamel. However there were heavy casualties amongst 9th Battalion and the adjacent 12th Battalion, and the Irish had to return to their starting positions leaving behind many wounded in no man's land. That night, Cather went out to locate and bring in wounded. He was able to retrieve three men before retiring for the night. The next morning he went out again to locate more survivors but was killed by machinegun fire. For his actions, he was awarded the Victoria Cross. The VC, instituted in 1856, was the highest award for valour that could be bestowed on a soldier of the British Empire. The citation for his VC read as follows: Originally buried near where he was killed, Cather's grave was later lost. His name is listed on the Thiepval Memorial to the Missing, which was established near Thiepval in Picardy. A plaque to his memory is on the walls of the main building of Hazelwood School, which he attended in his youth and he is listed on the Royal Fusiliers Regimental Memorial in St Anne's Cathedral in Belfast.
