Portillo went on to explain that the novel had won overall because of "its originality". He said that "The White Tiger" presented "a different aspect of India" and was a novel with "enormous literary merit".

Adiga had been given odds of 7/1 before the ceremony by bookmakers William Hill. Irish writer Barry had been tipped to take the prize at 7/4. The bookmakers' favourite has not won since Yann Martel in 2002.

Adiga was born on October 23, 1974 and raised partly in Australia. He studied at Columbia and Oxford Universities and is a former correspondent for TIME magazine in India.

His articles have appeared in publications such as the 'Financial Times', 'Independent' and 'Sunday Times'.

Adiga's book "The White Tiger", a tale of two Indias, tells the story of Balram, the son of a rickshaw puller in the heartlands, one of the "faceless" poor left behind by the country's recent economic boom.

It charts his journey from working in a teashop to entrepreneurial success.

The award, which honours the best fiction written in English by an author from the UK, Ireland or the Commonwealth nations, was handed out at the Guildhall in London.

The win means Adiga can expect an upturn in sales and added recognition.