"Mercifully, Mr Zimmerman survived the ordeal because, although he suffered three jagged wounds to the front of his neck, none of them caused any damage to any of the major blood vessels in that area."

Mire then went up to street level, where he came across Daniel Bielinski and his girlfriend, and again lashed out with his blade.

In an "extraordinary" act of bravery, instead of running away, Mr Bielinski took out his mobile phone and began recording, "at considerable risk to himself", Mr Rees said.

In the dramatic footage, Mire is shown lunging towards other Tube passengers.

Mr Rees said that none were seriously hurt, while one man, Andrius Sabaliauskus, showed "great courage" in trying to calm Mire down.

Mr Bielinski continued to film events until police arrived and tasered Mire.

The court heard Mire accepts he used the knife and has pleaded guilty to wounding Mr Zimmerman with intent to cause grievous bodily harm and to attempting to wound four other Tube passengers.

But Mire denies the charge of attempted murder.

Somali-born Mire had suffered from mental illness for years and arrived in the UK as a young boy, the court heard. At the time of the attack, he was living alone on benefits in a flat near the Tube station in east London.