The love affair that left man of chastity exposed

In December 1920, when he was 51 years old, Mahatma Gandhi sat down and composed a love letter. 'I have been analysing my love for you,' he wrote. 'I have reached a definition of spiritual marriage. It is a partnership between two persons of the opposite sex where the physical is wholly absent.'

The letter, to a beautiful writer called Saraladevi, marked the end of a significant love affair in the life of the Indian freedom movement leader. Though the relationship was never physical, it threatened his marriage and his work - and it left Saraladevi heartbroken.

Gandhi's love affair is revealed in a new biography written by his grandson, Rajmohan Gandhi. Mohandas: a True Story of a Man, his People and an Empire, was published in India last week but has yet to be released in Hong Kong.

'I wanted to capture the real man in my book, so I couldn't leave this episode of my grandfather's life out,' says Rajmohan, whose father, Devadas, was Gandhi's youngest son.

'Though a popular metaphor - 60 years after his death - for innocence, ingenuity or courage, he is not clearly known as a person,' Rajmohan writes of his grandfather in the introduction to his book. Using diary jottings, letters, articles, memoirs and his family's archives, Rajmohan, who is a lecturer at the University of Illinois in the US, has set out to demystify the man who helped to end three centuries of British colonial rule in India.

'Previous biographies have tended to focus on particular aspects of his life,' says Rajmohan. 'I think that this book tells the whole story, and I hope that in some way, it captures the man.'