As Dean and then later Emeritus Lecturer in Medicine, he was a major participant in the move of King's College Hospital from Lincoln's Inn Fields to Denmark Hill in 1933, an achievement for which he was awarded a knighthood.

Simultaneously, in his roles on its council, he raised the profile of Epsom College, secured the admission of women to the benefits of the Royal Medical Foundation, improved pay for masters and founded a building dedicated to learning biology.

An illness in his early forties left him with mobility difficulties, causing him to stop clinical practice and turn to writing a number of history of medicine articles and historical books, including one on the controversial death of Charles II.

He gave the FitzPatrick Lectures in 1911 and 1912, the first which was expanded into one of the most comprehensive accounts of the royal touch and scrofula (the King's evil) and the second into a book about Plague in art and literature.

[2] He subsequently studied medicine at Kings College Hospital Medical School, London, where he was awarded both junior and senior scholarships and then passed the B.M.

[2] At the turn of the 19th century, he became Registrar to the Royal College of Physicians (RCP),[3] a position he retained for thirteen years.

[3][2] In 1925, he became a representative on the committee of management of the Conjoint Board, which later, in 1937, sent him to visit the Medical faculty of the Egyptian University, to report on its progress.

In addition, Crawfurd later helped Lord Dawson search for a new site for the RCP in the planned move from Pall Mall East.

[1] He secured the admission of medical women to the benefits of the foundation, influenced acts of parliament and made administrative changes.

[7] In his early forties, a chronic illness affecting his bones and requiring surgery to one of his knees,[2] left Crawfurd immobile and incapable of medical practice and he turned his interest to writing and the history of medicine.

His works included The Last Days of Charles II (1909), The King's Evil (1911) and Plague and Pestilence in Literature and Art (1914),[1] a topic he had lectured on the previous year at an international congress.

It had therefore received much attention over the years and Crawfurd’s publication, The Last Days of Charles II (1909), became a respected revision of the facts.

[16] Monarchs of England and France were the only Christian royals to practice this "gift transferred by the Gods",[16] (due to the high esteem in which God held the royals) and historians have dealt with the matter from various angles, from "ridicule"[16] and "absurd",[16] to Crawfurd's fascination, in what Sturdy describes as Crawfurd's "dubious if exotic"[16] views.