John Hayward was a pioneer, specialising in breast surgery before this was a recognised discipline. He was as much a scientist as a surgeon, bringing rigour to the investigation of the causes and treatment of breast cancer. The son of an architect, he was born on 26 April 1923 in Westcliff-on-Sea, Essex, and was educated at Haileybury School. At his father's suggestion he gave up the idea of a stage career, spending most of his life in a different theatre. He trained in medicine at Guy's Hospital during the Second World War and went to Belsen concentration camp after it had been liberated. This experience clearly had a profound impact upon him, possibly shaping the way in which he established a highly effective method of caring for anxious patients. After graduating in 1947, his National Service was spent in the Royal Air Force. In 1953 he was appointed as an assistant surgeon at Guy's, working with Sir Hedley Atkins. At that time the major research interest was endocrine manipulation for the control of advanced breast cancer and his early research focused on adrenalectomy and hypophysectomy, both procedures being associated with substantial morbidity. The turning point came in 1957 when he met Richard (Mick) Bulbrook, an endocrine biochemist working at the Imperial Cancer Research Fund (ICRF). Hayward and Bulbrook formed a working partnership, with the former taking blood and urine samples from patients, which were analysed by the latter. Between them they developed a discriminant function test to determine which patients would benefit from endocrine surgery. Furthermore, low levels of certain urinary steroids indicated a poor prognosis, which raised the question of whether this abnormality could have a causative role in the evolution of the disease. This prompted the Guernsey study, with the aim of collecting specimens from a large stable population with good medical care and accurate follow-up information. The project started in 1961. Other much larger epidemiological projects occurred later, but this was the first of its kind in the world. Long-term analysis indicated that different endocrine profiles predicted risk in pre- and post-menopausal women. Specimens from the Guernsey study continue to yield important data concerning risk factors for breast cancer. In order to combine laboratory research and clinical investigation, the ICRF supported the building of a 37-bedded breast unit at New Cross Hospital in the 1960s and John Hayward was appointed director in 1967. He set about gathering around him a dedicated team of individuals specialising in breast cancer research and he established the multidisciplinary team as the underpinning of this work. He wanted to test surgical techniques for avoiding mastectomy, and he and Sir Hedley Atkins set up the Guy's wide excision trials. These trials compared radical mastectomy and radiotherapy with wide excision and radiotherapy, without any axillary surgery. The first trial included clinically node positive cases, whereas in the second only those with clinically negative axillae were randomised. Unfortunately, because of the low radiation dose to the axilla, these trials showed that breast conserving treatment was inferior to mastectomy in terms of local control and overall survival. This strongly influenced his views on the need for adequate axillary treatment. A subsequent trial comparing modified radical mastectomy with wide excision, axillary clearance and breast irradiation showed similar survival in both groups and was, with other trials, influential in changing surgical treatment for selected patients with breast cancer. He was recognised as an international authority on breast cancer, and was in great demand at medical conferences, where he was a lively and stimulating lecturer and chairman. He was a founder member of the British Breast Group and, in combination with Mick Bulbrook, could be guaranteed to bring wisdom and wit to the meetings. Such was the respect in which he was held that the Union for International Cancer Control (UICC) invited him to chair the multidisciplinary project on breast cancer in the 1980s, and he was able to gather together the world experts on the disease. The aim was to determine strategies for the prevention, detection and management of breast cancer and to define directions for future research. He was much admired by his patients because he had the ability to make them feel that they were the sole individual who mattered. As a colleague he was a delight because his concerns were to get the treatment right and foster an atmosphere in which high quality basic and clinical research could flourish. That was his legacy. He died on 24 February 2013 aged 89. He was survived by his wife Jill and two sons.