John Adolphus was of German background. His grandfather had been domestic physician to Frederick the Great, and wrote a French romance, Histoire des Diables Modernes. His father lived for a time in London supported by a wealthy uncle, who provided the son with education, and sent him at the age of fifteen to be placed in the office of his agent for some estates in St. Kitts. Adolphus returned to London after something over a year, and was articled to an attorney. He was admitted an attorney in 1790, but after a few years began to write.


The success of his history and the influence of Archdeacon William Coxe brought Adolphus into close connection with Henry Addington, then prime minister. Addington put him on a salary, for political services which included electioneering and pamphleteering. He entered the Inner Temple, and in 1807 he was called to the bar.


He wrote several books, his most well known was the History of England from the Accession of George III to the Conclusion of Peace in 1783.
The image opposite is an 1804 mezzotint in the National Portrait Gallery