He drew on his medical background in writing his books, and his most popular character was Doctor Finlay, which provided the background for the television series, Doctor Finlay's Casebook. A chronic duodenal ulcer prompted a career switch and he began writing books, TV and film scripts, including the Oscar-nominated The Citadel.

The first, Adventures of a Black Bag contains short stories first published in a magazine in the 1930s and first brought together in a book in 1945. Pan Macmillan acknowledges the Traditional Custodians of Country throughout Australia and their connections to lands, waters and communities. After the war, he investigated occupational diseases in the coal industry and worked as a general practitioner in Wales and London. Set in a local medical practice in the fictional post-war Scottish village of Tannochbrae during the 1920s, this BBC medical drama became one of the most popular programmes of the 1960s, inspiring other popular series such as Doc Martin and All Creatures Great and Small.

Alternatively, the main character will be someone who is suffering unnecessarily, and Dr Finlay will help them to overcome their affliction. Pretty boring, the doctor is given zero context as a character (despite being the main one), and the dialogs - gosh, real human beings don't talk like that.

As with many short story collections these were (I believe) originally published in magazines and never really intended to make a story arc - indeed rather like the stories of Sherlock Holmes they do contradict each other here and there. I can see how it very much worked for a weekly television serial but sadly, unlike the Citadel it doesn't seem to have stood the test of time as well. At the time the stories were set, some time before the Second World War, a local doctor had a great deal of sway in the area of his practice and many of his patients looked to him for advice in all sorts of matters.This is, however, part of his charm; it is certainly easy to see why Dr Finlay has remained such a popular character over the years. There are a couple of other recurring characters who deserve a mention, primarily because of their strong characters. In 2001 and 2002, BBC Radio 4 broadcast a version of the original Cronin stories using the titles, The Adventures of a Black Bag and Doctor Finlay – Further Adventures of a Black Bag; these have been rebroadcast by BBC 7.

Very similar in format to James Herriot’s All Creatures Great and Small, each chapter revolves around a new medical case or community problem. Andrew Cruickshank is the crusty senior Doctor Cameron and Barbara Mullen is the unflappable Janet, housekeeper at Arden House medical practice. The "stories" are only a few pages long, and feature Finlay in the midst of some moral dilemma, though -- don't worry!Cronin wrote two collections of stories which are recorded here together: Adventures of a Black Bag and Dr Finlay of Tannochbrae. Other outdoor scenes were filmed in Kilbarchan, Church Street in particular has changed little since filming took place.