93-year-old doctor still teaches surgery.

Ellis was born in 1926 to a family where his father was a barber and his mother a seamstress. He was one of the longest-serving medical professionals in Britain and saved the lives of thousands of patients.

In July 1948, the National Health Service (NHS) was established. Around this time, Ellis graduated from Oxford University's Faculty of Medicine and began working at the NHS, while also completing his surgical residency at Radcliffe Hospital, Oxford.

After completing his residency, he became a surgeon, working at various hospitals in major cities such as Oxford, London, Sheffield, and Northampton. From 1960 to 1989, Ellis was the chief surgeon and professor of anatomy at Westminster Hospital.

At the age of 63, Harold began teaching Anatomy at Cambridge University. After some time, he transferred to Guy's Hospital in Southwark, London, where he has worked ever since. Today, the professor still teaches weekly from Monday to Friday.

Ellis said he was happy to have dedicated his life to the NHS and was content with his current teaching job, which allowed him to witness many changes in the medical field.

"People's expectations for healthcare today are much higher than they used to be. When I first started my career, living to around 60 was considered very long life. In addition, the cost of medicine and medical equipment was also cheaper than it is today," he shared.

The professor has no intention of retiring yet. "I always tell my colleagues to tell me when they think I'm too old, and then I'll retire," he said.

Besides teaching, Harold also wrote hundreds of articles and books.Stories from the Operating Theatre and Other EssaysThis is his latest book, a medical textbook.Clinical AnatomyThe works he compiled have been reprinted 13 times.