General service whistle on lanyard : Sergeant L W Thompson, 21 Battalion, AIF

Standard police-pattern nickle-plated tube bodied whistle with opposing windows, lead fipple and an integral suspension loop. The words 'J. Hudson & Co / 13 Barr St / BIRMINGHAM / 1911 / Hudson's Patent [pair of facing broad arrow symbols]'. A plaited brown leather retainer with a sliding hangman's knot is attached to the suspension loop via a nickle plated metal swivel loop and fob clip. Both clips are corroded. The leather strap varies in profile, commencing at one end in circular profile and gradually widening to the flat.

General service whistle issued to and used by 1738 Sergeant Leslie Wilson Thompson who enlisted in the AIF as a private on 6 April 1915, aged 24 years and nine months. He was originally assigned to the 22nd Battalion, but was transferred to the 21st Battalion on July 1916. He embarked for overseas service and served at Gallipoli. After evacuation from Gallipoli, the battalion moved to France in March 1916.

Thompson was wounded in action on 26 August 1916 at Mouquet Farm near Pozieres and admitted to the 2nd Eastern General Hospital, suffering from 'a mild gunshot wound to the chest'. While he was recovering, Thompson was employed by the Australian Army Pay Corps as a lance corporal. This rank was reverted to private on his return to his battalion in France in June 1917. However, in September 1917 he was promoted to sergeant. On 21 September 1917, Thompson was wounded in action for the second time, likely during the battle of the Menin Road.

After recovering in hospital in England, Thompson returned to his battalion in France who were around the Ypes area recovering from operations. A few months later, in late May 1918, he underwent musket training on Hayling Island, England. The reports were very positive about Thomson, having 'good knowledge of musketry on arrival. very good progress during attendance. An excellent type of NCO. Good fit for musketry instructor position'. He returned to France after training in August possibly to the area around Hamel, Amiens and Mont St. Quentin. After losing so many men in the 1918 offensive on the Western Front, the 21st Battalion was no longer able to muster a company. They remained together for their last battle on the on 5 October at Montbrehain before being disbanded on the 13th October 1918; it was the last battalion to withdraw from active campaigns. Thompson was transferred to the 24th Battalion and returned to Australia onboard the 'Traz-os-montes' on 8 April 1919.

As a sergeant and a platoon's second-in-command, Thompson would have used his whistle in action as a aid to commanding his platoon; usually only a small number of whistle blasts were used to indicate pre-designated commands - one, two or three blasts to indicate simple movements such as advance, stop or withdraw.