A former governor of Punjab, Sir Michael O'Dwyer, was killed by an Indian immigrant in London in 1940. The assassin, Udham Singh, said he was avenging the deaths of hundreds of civilians who had been fired on by colonial troops in Amritsar in India in April 1919. When he was put on trial at the Old Bailey, he gave a defiant speech against colonial rule. Sajid Iqbal has been speaking to Avtar Singh Jouhal who campaigned to have Udham Singh's courtroom speech made public.

Photo:An Indian man takes a photograph of a painting depicting the Jallianwala Bagh massacre in Amritsar. The Amritsar massacre, also known as the Jallianwala Bagh Massacre, took place on April 13, 1919 when British Indian Army soldiers on the direct orders of their British officers opened fire on an unarmed gathering killing at least 379 men, women and children, according to official records. (Credit: NARINDER NANU/AFP/Getty Images)