Peter was born in Sydney in 1945 to Molly and Richard Barrett. He was the second eldest of six children, having three sisters and two brothers: Kathleen (pharmacist), Phillip (medical practitioner), Vincent (solicitor), Christine (solicitor and now a mathematics teacher) and Patricia (school teacher). He completed his schooling with distinction at Marcellin College, Sydney, in 1961, coming eleventh in the Leaving Certificate Examination in the state. He was the recipient of a foundation scholarship in medicine at the University of New South Wales in 1962.

His residency at Prince Henry Hospital, Sydney was followed by a short period in private practice. In 1973 he married Robyn Dougherty, also a doctor, and together they travelled to South Africa where Peter continued his training in cardiology at the Johannesburg General and Baragwanath Hospitals. He went to work with Leo Schramoth who was a leading teacher of electrocardiography. This period of his career was to prove crucial in the development of his passion for the electrocardiograph which was to dominate his medical career. His analytical and logical mind were perfectly suited to unravelling the rhythms of the most complex and confusing electrocardiograms.

After leaving South Africa, he travelled to the United Kingdom where he worked as a cardiology registrar at the National Heart Hospital in London, making a reputation for himself in electrocardiography and pacemakers. He then travelled to Los Angeles to pursue work in electrophysiology of the heart, a completely new and emerging field in cardiology at that time. He was able to integrate his profound understanding of electrocardiography with the laboratory science of electrophysiology of the heart. In this sub-speciality he was invited to lecture to both students and consultants. Subsequently he was elected a Fellow of the American College of Cardiology in 1979, and a Member of the North American Society of Pacing and Electrophysiology in 1983.

From Los Angeles, Peter was appointed Senior Staff Cardiologist at the St George Hospital, Sydney in 1978. He also became secretary of the New South Wales Division of the Cardiac Society of Australia and New Zealand in the same year. Peter brought with him a passion for hard work, a vision of the future in cardiology, a logical and legalistic mind and brand new skills. These were pioneering days in the Department with little money and few facilities. However, the Department grew over the years both in the services it delivered to the community and its teaching and training commitments to future cardiologists. The Department was involved in the teaching of more than two dozen Advanced Trainees who become fully fledged clinical cardiologists recognised by the Royal Australasian College of Physicians. Peter’s role in this was seminal and was vital to its success.

In 1985, Peter and others in the Department at the time were instrumental in introducing cardiac surgery to St George Hospital. Peter became the St George Hospital representative of the Public Medical Officers' Association. In this role he achieved recognition of staff specialists' rights and conditions of work at both the hospital and state level. He adjudicated many disputes within the Hospital and gained the respect of the administrators for his sense of fairness and clear understanding of the issues involved. Peter was an inspirational teacher at undergraduate and post graduate level. He lectured without notes, using carefully selected slides to succinctly demonstrate the finer points of an ECG. He always emphasised to both junior and senior medical staff working with him the primacy of the patient. He published over 30 papers and abstracts during his life in national and international journals. In 1996, he became a visiting medical officer in cardiology at the St George Public and St George Private Hospitals in Sydney.

Peter was charismatic and mercurial with a rare quality for being self-critical. On the other hand he had a wonderful sense of humour, often laconic, at times cynical, and frequently pointed and profane. This was often accompanied by pantomime in classical burlesque style. His humour was infectious and his laughter incredibly engaging. He was a natural entertainer and often brought relief to a stressful day. Outside medicine, Peter was a good cricketer, tennis and squash player and he loved bush walking.

Peter died unexpectedly from cardiovascular disease in August 2003 whilst on holiday in Sri Lanka. To honour him, the Cardiac Catheterisation Laboratory in St George Hospital has been named after him. He leaves behind his wife, Robyn, and children Brendan, Emma and Tim.