The Punjabi boy had ascended due to the death of his father, the Lion of Punjab, a.k.a. Ranjit Singh.
The boy ruled (sort of, he was five after all) for five years until war broke out and Britain got involved. The result was in 1849 Punjab was annexed to British India, and the boy was removed from the throne thus becoming the last ruler of the Sikh kingdom.
Duleep Singh’s mother (who was pretty much in charge) was imprisoned and Duleep Singh ended up in the guardianship of a British army surgeon and his wife. From tea and crumpets to Christianity, the couple taught him the way of the English.
In 1854, Duleep Singh and the doctor’s family went to England, and Duleep Singh met and charmed Queen Victoria. He was such a hit he became a kind of brother from another mother in the royal household: everybody wanted to hang with him, and he even went on holiday with the Queen and Prince Albert.
If you stopped the tale there you would still have a really good story, but an incomplete one.
A new film The Black Prince picks up the ball and completes the play, delivering the full story of Duleep Singh.