Llewellyn was one of the five children of John Townsend and Catherine Raworth Bucknill. He was educated at Wellington College and the Royal Military Academy at Woolwich and on 24th September married Mary Ashton Shuttleworth in St Michael’s Church, Hathersage in Derbyshire.
Llewellyn had listed with the Royal Field Artillery and became a Second Lieutenant on 12th May 1900. He was promoted to Lieutenant in April 1901 and served in Northern Nigeria from April 1907 to June 1908. He became a Captain in February 2010 and served with the 22nd Brigade in South Africa from September 1912 to August 1914.
Llewellyn embarked for France with the 22nd Brigade on 5th October 1914 and was promoted to Major on 30th October 1914. Two weeks later he was appointed as the Officer Commanding 105th Battery, 22nd Brigade. He died on 18th May 1915 in Bethune Hospital, three days after being wounded in the spine at the Battle of Festubert in the Artois region of France.
An account of his death given on the Great War Forum website states that:
“Major Bucknill was … advancing with his signaller, Gunner Sheffield, endeavouring to lay a wire from a drum and establish an advanced observing station in the trench captured by the Infantry, which had gone forward to another German trench”.
His entry in De Ruvigny’s Roll of Honour states that Major Llewellyn was twice mentioned in Despatches. The first was on 17th February 1915 for his services during the early fighting at Ypres, and the second on 1st January 1916.