He continued his education at Try Boys’ Society South Yarra and by reading at Prahran Free Library where he met Maurice Blackburn.

[2] As a socialist, Slater refused to enlist with voluntary the Australian Imperial Force (AIF) at the beginning of World War I.

[3][4] Slater left Melbourne with his unit in June 1916, arriving in Plymouth, England in August of the same year.

[2] The Argus newspaper later reported that fellow patients at the hospital mistook his appointment as a Member of Parliament as being a promotion to the Military Police.

Returning to Australia he was arrested by military police in Fremantle for speaking in defence of John Curtin, then the editor of a trade union newspaper.

[2] At the 1932 state election, Slater was defeated in Dundas by United Australia Party candidate Athol Cooper.

En route to his new appointment he visited the United States, eventually arriving in the Soviet Union in late 1942.

Although the official reason given for his early return was illness, speculation in the Australian press centred on a disillusionment with the Soviet version of Socialism.

William “Bill” Slater joined Australian Natives' Association (ANA) in 1918, just after his return from overseas service in World War 1.

He represented ANA’s position on immigration in Parliament in 1958[11][12] On 19 December 1923 he married Mary Gordon, aged 26, who was a senior botany demonstrator at The University of Melbourne.

[13] He was a Trustee of the Melbourne Cricket Ground (MCG) for 30 years and a Vice President of the Essendon Football Club (VFL) and he was involved in many community activities.