Walter Leslie Monk, known as Leslie to his family and friends, was born on Wednesday, 15th June 1898 in Chippenham, Wiltshire, the only son of Charles Walter Monk and Agnes Emily Duck. When Leslie was born, his father Charles was a live-in Caretaker at Darley Nether Hall, a large manor house in Hathersage, Bakewell in Derbyshire.

By 1911 the family had moved to Shendish House at Kings Langley, Hertfordshire where Leslie’s father was employed as a Chauffeur for the Longman family of publishing fame. Meanwhile young Leslie was at school in Greenwich in London.

He attended the Royal Hospital School for Sons of Seamen which was historically nicknamed ‘The Cradle of the Navy’ and entry to the school was limited to the children or grandchildren of seafarers. At the time of Leslie’s attendance, boys of the school were also required to join the Royal or Merchant Navy, and as such the education was focused on maritime matters. The naval traditions of the school were considered so significant that its impact in British history was stated as follows: "Just as, according to the Duke of Wellington, the Battle of Waterloo was won on the playing fields of Eton, it may justifiably be claimed, that the establishment of... the British Empire, was charted and plotted in the classroom of... the Royal Hospital School."

Leslie enlisted as soon as he had completed his education, joining up as ‘Boy 2nd Class’ in the Royal Navy on the 20th November 1913 aged fifteen and was posted to HMS Ganges, the Navy’s on-shore training establishment at Shotley in Suffolk. He had signed on for twelve years and his ‘Period of Engagement’ was due to begin on the 12th June 1916. However, events overtook and by October 1914 Leslie had been trained as a Telegraphist and posted initially to HMS Vernon before transferring to HMS Invincible at the end of November 1914.

It took Leslie five months to train as a Wireless Telegraphy Operator. He began by learning Morse code and the Navy's methods of sending and receiving signals. To pass out at the end of the course he had to be able to read at twenty-two words per minute and transmit at ten words per minute. Telegraphists were also trained in coding since there were very few coders at the beginning of the war. Telegraphists were indispensable to the Royal Navy in the early days of wireless technology. According to a report in the Hemel Gazette Leslie’s abilities led to promotion at a young age.

Invincible was a battlecruiser and the lead ship of her class of three when built in 1907, and the first battlecruiser to be built by any country in the world. Leslie participated in the Battle of the Falkland Islands where Invincible and her sister Inflexible sank the armoured cruisers Scharnhorst and Gneisenau almost without loss to themselves, despite numerous hits by the German ships.

She was the flagship of the 3rd Battlecruiser Squadron during the Battle of Jutland and during the battle Invincible was struck amidships, detonating the magazines below and causing her to blow up and sink. All but six of her crew of 1,032 officers and men were killed. Leslie died when the Invincible was destroyed on Wednesday, 31st May 1916.

His death and a brief obituary was published in the Hemel Gazette shortly after he was killed.

Leslie is Remembered with Honour on the Portsmouth Naval Memorial, Hampshire, United Kingdom, Panel 15.

He was only 18 years old when he died. 

Leslie was eligible for the 1914-15 Star, the British War Medal and the Allied Victory Medal.