A bust of the last Sikh emperor, the dashing son of the legendary Lion of Punjab, is to be auctioned in London in April and is expected to attract huge interest from Sikhs around the world.

The story of Maharajah Duleep Singh is as tragic as it is romantic. Born into fabulous wealth, kidnapped as a boy by British imperialists 150 years ago, forcibly converted to Christianity and brought to England, he was stripped of his empire, adopted as an exotic talisman by Queen Victoria, was disgraced and disowned and eventually died, a pauper, in ignominious exile. Three overgrown graves in a Suffolk churchyard are all that remain of one of the proudest dynasties to rule India.

Duleep Singh was charming, handsome, reckless and scandalous. In his heyday he was an intimate of dukes and earls, a favourite guest at Victorian shooting parties. He owned a grand estate and lived the life of a country gentleman. The Queen showered gifts and affection on him, as did the Prince Consort. The Government paid his gaming debts and courtesans vied for his attention. But when he died, after thwarted attempts to regain his throne, he was forgotten even by his countrymen. None of his eight children ever returned to rule the ancestral homeland. None produced any children. All that remains of his wealth is the Koh-i-noor, the fabulous diamond that he once placed in Victoria’s hand and which now adorns the late Queen Mother’s state crown.

In 1859, five years after his arrival in England, he sat for the celebrated sculptor and Royal Academician John Gibson, who fashioned an exquisite marble bust showing the young maharajah at the height of his fame, beauty and glory, wearing a pearl necklace and embroidered kaftan tunic. It will be auctioned at Bonhams on April 19, and is expected to fetch up to £35,000.

When Duleep Singh was born in 1838, Britain was engaged in a fierce struggle for Punjab. His regent mother led a revolt, which was crushed. The British imprisoned her, annexed Punjab, deposed the 11-year-old maharajah in 1849 and entrusted him as a ward of the Government to a Scottish army surgeon. He was granted an annual allowance of £40,000.

Baptised a Christian in 1853, he sailed for England a year later. He played cricket, wore European dress (always with three rows of enormous pearls) and learnt the ways of an English gentleman. The Queen received him at Buckingham Palace and was enchanted. Prince Albert designed a coat of arms for him. He made friends with the Prince of Wales, was given a Bible by Lord Dalhousie (the conqueror of Punjab and jailor of his mother), tutored in German and Italian and given a residence, first in Wimbledon and then at Roehampton.

But he soon palled of the social whirl and yearned to go back to India. The Government was wary, but he set sail in 1861 and had an emotional reunion with his embittered mother. Persuaded to return to England, he stopped off in Cairo and met the 16-year-old Bamba, daughter of an Abyssinian and a German banker and married her — although they had to talk through an interpreter.

They set up residence at Elveden Hall, in Suffolk. But his life became dissolute. He took mistresses, fathered illegitimate children, ran through his allowance and begged for more. Fired by his late mother’s stories of British injustice, he wrote a book on Britain’s plunder of India and, determined to regain his throne, left for India in 1885. A year later he was re-initiated into Sikhism. But a spy was planted in his entourage and learnt, to government horror, that he had approached the Russians to help reconquer Punjab. Nothing came of it, although he spent a miserable two years in Moscow. Eventually he had to return, and in an emotional meeting with Queen Victoria, wept and begged official pardon.

By now he was a broken man. Bamba had died and he had married his mistress Ada, a chambermaid he met at Cox’s hotel in Jermyn Street. In 1893 he suffered an epileptic fit and died in Paris. His funeral at Elveden had a wreath from the ever-indulgent Queen and another from the Prince of Wales “for auld lang syne”. His children forged indifferent careers. The Eton-educated Victor gambled away his money, his sober second son Frederick became a Suffolk squire and one daughter, Princess Sophie, became a suffragette. The eldest daughter, Princess Bamba, died, a recluse, only in 1957. By then their homeland had been partitioned between India and Pakistan. And with her died the dynasty of the warrior Sikhs.