William Hasted was born at Waltair, Madras in India on 28 September 1897, son of William Anderson Hasted, an official of the Indian Civil Service who was Director of Survey, Madras, and his wife, Mabel Jessie (née Field). He was educated at Cheltenham College, 1910-1914 and the Royal Military Academy, Woolwich, October 1914-April 1915, before being commissioned into the 5th Field Company of the 2nd Division of the Royal Engineers. Hasted served in France and Belgium during the First World War between early 1916 and November 1918, and was gassed and twice wounded, also being twice mentioned in despatches and receiving the Military Cross in November 1916.

After the war, Hasted's leg was badly broken during a celebratory rugby match between the British Army and the Australian Army and he was sent to the War Office to help with demobilization. In 1919 he returned to the Royal Engineers and was sent to Ireland to fortify the Police Barracks against attack, before finishing his education at Peterhouse College, University of Cambridge, 1920 and the School of Military Engineering at Chatham from 1922-1923.

In 1920 Hasted married Hella Elizabeth Mary (she died in 1961), daughter of Lieutenant-Colonel Arthur Cuming, of Doneraile, County Cork, Ireland; they had no children. Some time after the war, Hasted became an Instructor of Military Engineering, first at the Royal Military Academy, Woolwich, 1924-26 and then at the Royal Military College of Canada, in Kingston, Ontario, 1926-30, also representing the Army, Combined Services and England at field hockey and becoming badminton doubles champion of Canada. He then returned to army life, serving as Garrison Engineer at Tidworth [Wiltshire], 1930-32, then OCRE South Irish Coast Defence, 1932-36. Hasted was posted to India's North West Frontier with the Bengal Sappers-Miners (Peshawar) in 1936, before being appointed to northern command headquarters in 1937. He distinguished himself in the Waziristan Operations during 1937 (he was mentioned in despatches twice and was awarded the DSO) and became commander of the Royal Engineers in the Waziristan District, 1938-1940. He was mentioned in despatches again and became a CBE following the Waziristan Admadzai Operations in 1940, then Deputy Chief Engineer at Northern Command headquarters of the 10th Army, first in India in 1941, and then in Iraq, Syria and Iran, 1941-42. Hasted was then appointed Deputy Engineer-in-Chief (Air), at General Headquarters in New Delhi, 1942-43, taking charge of airfield construction, during which time 220 airfields, depots and stations were built and Hasted was awarded the CIE. He then became Chief Engineer of the Southern Army in India, 1943, and Chief Engineer of the 14th Army in Burma [later Myanmar], from 1944-45, for which service he was twice mentioned in despatches and awarded the CB. Under Hasted, a further 59 airfields were built, and the Kabaw (Death) Valley BITHESS Road constructed through virgin jungle over 112 miles in 135 days. The River Chindwin was crossed at Kalewa on the 10th December 1944 when the longest Bailey Bridge (350m) ever assembled was placed across the river in 28 hours. The Kalewa boatyard was established and 541 boats, barges and rafts were built to ferry the 14th Army across the Rivers Chindwin and Irrawaddy. Hasted then served as Chief Engineer for the Allied Land Forces of south-east Asia command, 1945-46, before ending his military career as Engineer-in-Chief in India, 1946-47, the last Engineer-in-Chief India under the British Raj.

Hasted retired from the Army in 1948. After a brief spell as Controller of Aerodromes for the Ministry of Civil Aviation, 1947-48, and the inaugural President of Loughborough College, Leicestershire, 1950-51, he became the first Controller of Development for Kuwait in 1952. His proposed 15 year expenditure plan for Kuwait’s national development was accepted by the Sheikh and Hasted oversaw the development of new schools, water distillation plants, power stations, a new port at Shuwaikh and the beginning of Kuwait Airways, which was launched in 1954, in the same year as his retirement from the Persian Gulf.

Following this second retirement, Hasted remained active, purchasing a dairy farm in North Devon in 1955, marrying Catherine Levis in 1961 after his first wife's death, then emigrating to Australia in 1963 with their two sons. He joined a civil engineering firm in the following year, then in 1966 spent time renovating an old house in Australia and in 1968 obtained a taxi-driver's permit and drove a taxi for one year. In 1969 he returned home to renovate his old family home in Suffolk, before opening licensed premises in 1975, two years before his death on 29 October 1977.