|Doctor John "Mossy" Lawn|
|Age||Currently in his 60s (already a doctor in Night Watch)|
|Occupation||Doctor, Chief of Medicine at the Lady Sybil Free Hospital|
|Residence||formerly Twinkle Street|
|Cameos||Going Postal, Unseen Academicals|
Dr. John Lawn, usually called "Mossy", is probably the only medical doctor in Ankh-Morpork actually known to cure or heal anyone. Normally, doctors are more to be avoided than the plague: the plague may not kill you, and certainly won't charge you for it.
Lawn credits his training in Klatch, where patients were expected to get better; he had learnt techniques other Morporkian surgeons distrusted, but which kept patients alive for longer than it took to pay the bill. He also gave free treatment to those who needed it, including those who had been tortured by the Cable Street Particulars.
While he is unlikely to give his patients a little trim or a shave when performing surgery, he makes use of a number of curious and often alarming implements in his line of work. Being outside the medical establishment, he worked for many years in a rough area near The Shades as a "pox doctor," with many patients among the Seamstresses.
In Night Watch he met and treated John Keel (and let John Keel (Sam Vimes) sleep in his spare room), and served as the surgeon for the short-lived army of the Glorious Revolution. When Sam Vimes returned to the present time in Night Watch, he found his wife in life-threatening labor with their first child. Vimes literally flew to Twinkle Street to get the now-thirty-years-older doctor, and rewarded his success (and his silence as to the real identity of "John Keel") with "one-hundred thousand dollars and the freehold of a large corner site in Goose Gate" near the old city wall. By the time of the events of Going Postal, the sprawling building had become the Lady Sybil Free Hospital.
Mossy continues as Chief Of Medicine there, apparently still fighting off the non-professional attentions of the nursing staff despite advancing middle age. Dr Lawn's preferred method of dealing with the nursing staff is to throw a handful of chocolates in one direction and run in the other as fast as possible. It is also noteworthy that he also serves as the family doctor (of sorts) to the Vimes family, Lady Sybil having mentioned that Dr. Lawn has told Sam Sr. at his latest physical to eat more fruit and vegetables - tomato ketchup doesn't count as such (trying to dissuade him from eating greasy food).
Later books have stated that the hospital is also used by Dr. Lawn to train new doctors in the same techniques that he had learned all of those years ago during his tour in Klatch. He is also known to employ Igorinas who wish to practice the full range of medical skills, not just assist their Igor counterparts. Tiffany Aching's friend Preston is one of his med students, now a surgeon in his own right (The Shepherd's Crown).
Dr. Lawn's personality can be described as quiet (if a tad sarcastic) and almost unshockable. During the events of the Glorious Revolution Lawn commented to John Keel (Sam Vimes) that, when he dies, he wants a bell left on his gravestone so he can have the pleasure of not getting up when people ring.
Lawn is quite possibly one of only two people (besides Vimes) who know the truth concerning John Keel: the other is the Patrician.