Sir Harold Gillies (June 17, 1882 – September 10, 1960) is a New Zealand otolaryngologist and widely considered to be the father of modern plastic surgery. Born in New Zealand, Gillies trained in England and joined the Army Medical Corps at the outbreak of war. Posted to France in 1915, he witnessed the rise in horrific facial wounds caused by the combination of heavy artillery and trench warfare, with soldiers peering over the parapets.

Upon returning to England, Gillies established a special ward for facial injuries at Cambridge Military Hospital in Aldershot. By 1916, Gillies had convinced his medical chiefs that a facial injury ward should be established at Cambridge Military Hospital, Aldershot.

Gillies established The Queen’s Hospital at Frognal House in Sidcup in 1917. It was the world’s first ever hospital dedicated to the treatment of facial injuries. The aim of The Queen’s Hospital was to reconstruct wounded men’s faces as fully as possible, so that they could hopefully lead a normal life.  

The Queen's Hospital opened in June 1917, and with its convalescent units provided over 1,000 beds. There, Gillies and his colleagues developed many innovative plastic surgery techniques; more than 11,000 operations were performed on over 5,000 men. The hospital, later to become Queen Mary's Hospital, was at Frognal House.

Antibiotics were not yet available, so successful reconstructive surgery was very difficult due to the risk of infection. Gillies and his team attempted ground-breaking procedures using grafted flaps of skin and transplanted bone ribs. Gillies famously invented the ‘tubed pedicle’, a technique that used a flap of skin from the chest or forehead and swung it into place over the face.

This pioneering work by Gillies and his team marked a huge advance in reconstructing the faces of severely injured men. It also laid the foundations of modern plastic surgery.

Between the wars Gillies developed a substantial private practice with Rainsford Mowlem, including many famous patients, and travelled extensively, lecturing, teaching and promoting the most advanced techniques worldwide.

In 1946, he and a colleague carried out one of the first sex reassignment surgeries from female to male on Michael Dillon. In 1951 he and colleagues carried out one of the first modern sex reassignment surgeries, from male to female, on Roberta Cowell, using a flap technique, which became the standard for 40 years.

According to Wikipedia & nam.ac.uk & rcseng.ac.uk