The various autobiographical details that Jack Whicher gives are correct. His father, Richard Whicher, was indeed a gardener, and Jack did indeed have a son called Jonathan who died young.
Captain Charles Shore says that he spent 12 years in India, the first five in the army, and that he left the army shortly after the Indian Mutiny of 1857 to 1858. This dates the events depicted to some time after 1865. Given the ages of the children, the episode probably takes place between 1865 and 1870.
The production was criticised, including by Kevin O'Sullivan of the Sunday Mirror and Alison Graham of the Radio Times, for being too darkly lit.