Ernest John Clinton Heathcote was born at Bathurst, New South Wales on 6 October 1901 to Ernest and Maria Heathcote. Heathcote wished to join the war effort but was underage. In May 1918, he travelled to Victoria Barracks where he enlisted under the name Frederick Whatson, claiming to be 19 years old and from the town of Bellingen. He was then transferred to Liverpool where he spent the next 20 days, until it was discovered he was underage. He was discharged in June 1918.
Heathcote then travelled up to Brisbane where he tried to enlist again in July 1918. This time he enlisted as Fredrick Manning Whatson and again gave his age as 19 years old and place of birth as Bellingen. He was given the service number 58180, allocated to the 6th General Service Reinforcements and became part of Queensland's 'Ryan's Thousand'. He embarked from Sydney on 4 September 1918 aboard HMAS Bakara with the rest of the Queensland reinforcements.

Upon arrival in England in November 1918, he was transferred to the 9th Battalion but by then the war had ended. Heathcote spent the next seven months in and out of hospital due to various illnesses including bronchitis, laryngitis and pharyngitis, while waiting to be demobilised home. In June 1919, Heathcote asked to be discharged from the AIF in order to join up with the British Army as part of the Russian Relief Force. He became part of the 201st Battalion, Machine Gun Corps and was given the service number 193042. This time he put his age up to 25. Heathcote details his time in the Russian Relief Force in his Private Record collection. He was transferred to Archangel and served in that region until a an encounter with the opposing force left him with a broken leg, dislocated elbow and injured foot. His injured foot turned gangrenous and had a high likelihood of being amputated.

Heathcote was invalided back to Australia on 29 August 1919.
Heathcote went on to join up with the New South Wales police force and married Daphne Ethel Evans in 1927. They moved around New South Wales until retiring to Palm Beach, Queensland in 1967. Ernest John Heathcote died in Brisbane on 14 March 1984.