In most parts of the world, physicians, surgeons, and all other medical practitioners are referred to as “doctor”. However, in the UK, surgeons are generally called Mr. or Ms. This is because as early as the Middle Ages, physicians were unable to practice medicine without embarking on formal university training. This degree was called a doctorate and entitled the bearer to the title of Doctor of Medicine.
Until the mid-19th century, the training of surgeons functioned very differently. They did not need to attend a university to obtain a degree. Instead, they worked as an apprentice to a surgeon, and then took an examination. In London, the Surgeon’s Company gave this exam after 1745 and after 1800 it was given by the Royal College of Surgeons. If they passed, the students were awarded a diploma, not a degree. So, not having a doctorate, the surgeons continued to use the title ‘Mr.’ like anyone else.
Outside the city of London and in the larger cities, surgeons started with an apprenticeship like many other tradesmen, but did not necessarily have to take an examination. Today, physicians, surgeons, and all other medical practitioners, must undergo training at a medical school to earn their degree. Then after that, a period of postgraduate study and training is needed to achieve the status of consultant surgeon. So the tradition of surgeons being referred to by regular honorifics. Essentially, the person starts as a Mr. or Ms., becomes a Dr., and then goes back to being a Mr. or Ms. again.