I want to know the answer to the following question:
How long was Karim in the Queen's employment?
All the background I'm provided with is that "Equerry Frederick Ponsonby (the son of Sir Henry) discovered that the Munshi had lied about his parentage, and reported to Lord Elgin, Viceroy of India, "the Munshi occupies very much the same position as John Brown used to do.". Is that enough to answer the question?