Adrian Brown, 38, was said to be suffering a severe psychotic episode when he stabbed Muhammed Ali in a London Overground carriage on 12 December.

The intervention of other passengers on the train, which was travelling between Honor Oak Park and Forest Hill, south London, might have saved the victim’s life, his trial at Southwark crown court heard.

Brown accepted he carried out the attack but pleaded not guilty to a charge of attempted murder on the grounds of insanity.