The only time British Monarch has become an emperor (or empress) is in India. Because, India had principalities of small doms goverened by the British officers but also had titular Princes. They actually made stamps of the 6 including that of Chandra Shamsher. here is what a philatelist tell about the stamps: "The Nawab of Murshidabad and the Maharaja of Balrampur were titled but their emindaries were part of British India, not Princely States. The maharajas and nawabs of such places had no sovereign powers as did the princes of true states. The Maharaja of Nepal is included, though Nepal was an independent kingdom, because of the history of friendship between the British Government and Nepal." nepal was independent throughout the history but not sovereign. Nepal was to British India just like what Mustang was to Nepal, until 1961.