Edward Jenner was, until recent years, badly served by his biographers. The first choice, although to all appearances well equipped for the task, ‘entered upon it’ as he confessed, ‘with a degree of anxiety in which I can scarcely expect any to sympathise’, and predictably made rather a hash of it. John Baron, a qualified physician and surgeon, first met Jenner in 1808 when he was fifty-nine and Baron twenty-three. They became and remained close friends and Baron was possibly the last person to see Jenner alive before his death in 1823. In view of their long and intimate acquaintance there was presumably some expectation or at least hope that Baron might play Boswell to Jenner's Johnson, but nothing could have been less likely.

A practical obstacle was the amount of time and labour involved:

A more deep-seated reason for the failure of the book lay in the relationship between the two men which, because of the age difference and Baron's deference in the face of Jenner's achievement and reputation, was more like that of father and son than of professional equals, even when later in life Baron himself had arrived at considerable eminence.