A rare oil portrait of the Indian anti-colonial activist Mahatma Gandhi was set to be auctioned for the first time in London's Knightsbridge district on Monday. Rhyanon Demery, a senior expert at Bonham's auction house, explained the portrait is believed to be the only oil painting of Gandhi he sat for. The portrait is currently valued between £50,000 and £70,000, but Bonham's expects it could sell for much more because of its rarity