Last Sikh sovereign of the Punjab; 1838-1893
Maharaja Duleep Singh
The youngest son of Maharaja Ranjit Singh, Duleep Singh became Maharaja at five and lost his kingdom at ten. He was brought up a Christian in English society, returned to the Sikh faith in 1886, tried to regain his throne, and passed away in Paris in 1893.
Child Maharaja
Born at Lahore on 6 September 1838, he was proclaimed Maharaja in September 1843 with his mother as regent. After two wars with the British he signed the annexation on 29 March 1849. Dr John Login became his guardian, and he was moved to Fatehgarh in 1850 and baptised a Christian on 8 March 1853.[EoS]
England
He reached England in May 1854 and was taken up by Queen Victoria. He married Bamba Muller at Alexandria on 7 June 1864 and they had six children. He lived at Elveden in great style, became known as a shot and ran into debt.[EoS]
Return to the faith
Thakur Singh Sandhanwalia came to him in 1884 and instructed him in Sikh teaching. He left for India on 31 March 1886, was stopped at Aden, and took the Sikh vows there on 25 May. He gave up his allowance and declared himself the enemy of the British government. He then sought help in Paris and at St Petersburg, while Thakur Singh and others worked for him in India.[EoS][EoS]
Last years
He had a stroke on his way back from Russia and passed away in a Paris hotel on 22 October 1893. His son Prince Victor took his body to Elveden for burial.[EoS]
What the sources disagree on
Images

Maharaja Duleep Singh as a boy, a miniature on ivory by a Company artist at Lahore, 1845.
Unknown, 1845. National Army Museum, 1961-10-9-16 (as credited on Commons). Public domain. Source

A drawing of the Koh-i-Noor by R.S. Garrard & Co., 1851, the year it was shown in London. It is from the Metropolitan Museum of Art's open access collection.
R.S. Garrard & Co., 1851. Metropolitan Museum of Art.CC0. Source

A 'true copy' receipt of 1851 recording the transfer of the Koh-i-Noor, said to have been made for Sir John Login and now in the Toor Collection.
Unknown, 1851. Toor Collection (as credited on Commons). Public domain. Source

Signing the Treaty of Bhairowal, 26 December 1846, with the boy Maharaja Duleep Singh, in a gouache of about 1846-1847. Commons links it to the British Museum.
Unknown, c. 1846-1847. British Museum, 1948,1009,0.109 (as credited on Commons). Public domain. Source