A veteran of World War I, Bostock first saw combat as a soldier in the Australian Imperial Force at Gallipoli, then as a pilot in the Royal Flying Corps on the Western Front, where he earned the Belgian Croix de guerre.

Bostock was born in Surry Hills, an inner-city suburb of Sydney, to an English father, also named William, and a Spanish mother, Mary.

After leaving school Bostock was employed as an apprentice with the Marconi Company for two-and-a-half years,[3] and spent time at sea as a wireless operator.

[5] Raised to sergeant, Bostock was posted to Egypt with the ANZAC Mounted Division in April 1916, and saw action against Turkish forces in the Sinai Peninsula.

The couple had two daughters, one of whom, Gwendolen Joan, would serve as a cipher officer in the Women's Auxiliary Australian Air Force (WAAAF) during World War II.

1 FTS), Point Cook, since entering the RAAF, Bostock was posted to Britain in 1926 to attend RAF Staff College, Andover.

[17] He was the RAAF's delegate to a defence conference in Singapore in October 1940; the Australian contingent found the local forces ill-prepared for an attack by the Japanese and recommended significant increases in air capability, both in Australia and the Pacific Islands, to meet the threat.

[10][22] He was also first choice of the incumbent CAS, Air Chief Marshal Sir Charles Burnett, whose two-year term was coming to an end.

[10] Bostock's closeness to Burnett, who had made no secret of his contempt for John Curtin's Federal Labor government, damaged his chances for selection and his friend, George Jones, then only a substantive wing commander and acting air commodore, took the position.

[10][23] Although he had expected to be made CAS, Bostock warmly congratulated Jones, possibly expecting that his (Bostock's) new role as chief of staff to the Commander of Allied Air Forces, Lieutenant General George Brett, with responsibility for air operations in the South West Pacific Area (SWPA), would prove the more important appointment in a time of war.

[24][25] RAAF Command was charged with defending Australia, except in the north-east, protecting the sea lanes to New Guinea, and conducting operations against Japanese shipping, airfields and other installations in the Dutch East Indies.

[28] On 14 September, Bostock had an audience with Prime Minister Curtin, wherein the latter outlined his preferences for the deployment of RAAF Command, particularly that it should be represented in forward Allied operations, and employed primarily in the support of Australian ground forces.

[30][31] Bostock wrote to Kenney, "I am particularly anxious that the 1st Tactical Air Force should continue to be employed as a forward offensive formation rather than in a garrison role.

[32] On Operation Oboe Six, the invasion of Labuan–Brunei in June, Bostock also had at his disposal aircraft based in Australia under Western and North-Western Area Commands.

His aim, in concert with that of Kenney and I Corps commander Lieutenant General Leslie Morshead, was to deliver the heaviest aerial bombardment possible against enemy targets, to enable Australian assault forces to land with minimal casualties.

Together with a naval barrage, this resulted in what the official history of the RAAF in World War II described as a "scene of indescribable ruin" on the battlefield, and allowed seventeen waves of troops to disembark their landing craft without loss.

[35] MacArthur called the Labuan air offensive "flawless",[1] and General Sir Thomas Blamey, Commander-in-Chief of the Australian Military Forces, congratulated Bostock on his "high order of control" and "ready and full cooperation" throughout the Borneo campaign.

[36] It was exacerbated by the fact that although the CAS was de jure head of the RAAF, Jones' rank of air vice marshal was no higher than Bostock's.

Air Force historian Alan Stephens later commented: "The system of divided command... was not an ideal arrangement, but with men of goodwill it could have worked.

Kenney threatened to escalate the matter to the Australian government, and some time later MacArthur told Curtin that Hewitt "was not an adequate replacement" for Bostock.

[43] Their feud was blamed for contributing to the low morale that precipitated the so-called "Morotai Mutiny" of April 1945, when a group of senior pilots in the First Tactical Air Force submitted their resignations rather than continue to attack what they believed to be worthless targets.

[44] When the pilots refused to drop the matter, Bostock signalled Jones, advising that he found morale on the island to be at a "dangerously low level" and recommending the CAS replace Cobby with Air Commodore Scherger.

[46] A subsequent investigation vindicated the stand taken by the pilots; one of them, Wing Commander Kenneth Ranger, told the inquiry of Jones and Bostock: "I deplore the fighting and wrangling between them which is common knowledge throughout the Air Force.

The conflict between the commanders reached its nadir during the invasion of Tarakan in May 1945, when Jones grounded RAAF bomber squadrons scheduled to take part in the attack due to their crews having exceeded their monthly quota of flying hours.

[38] Over all, the dual system of control and the tension between its two senior officers confused the RAAF's efforts in the field and reduced its influence on Allied strategy in the Pacific.

[50] Among the reasons for Bostock's dismissal were, according to private government papers, an "inability to work in harmony with certain other high ranking RAAF officers",[51] and "lack of balance and appreciation of responsibility".

He wrote a series of articles criticising the Air Force's organisation and presenting his side of the story of RAAF Command, motivated partly by his belief that the official history of Australia in World War II would fail to adequately cover it.

The articles caused considerable controversy and prompted the Minister for Air, Arthur Drakeford, to make a formal response in Federal Parliament, labelling Bostock's allegations "malicious and unjustified".