A man has admitted his involvement in a fatal attack outside the National Gallery in London.

Lucas Antunes, 21, pleaded guilty to the manslaughter of 51-year-old Desmond O’Beirne, who died six months after he was assaulted outside the landmark in Trafalgar Square last year.

Antunes, of no fixed address, had been extradited from the US before pleading guilty to the killing at the Old Bailey on Friday.

Lucas Antunes Lucas Antunes pleaded guilty to manslaughter (Metropolitan Police/PA)

A second man, aged 22, is due to appear at the court on Friday, also charged with manslaughter.

Police launched a public appeal for information after Mr O’Beirne, from Westminster, was left in a critical condition hospital following the attack in the early hours of June 3 2017.

Desmond O’BeirneDesmond O’Beirne died six months after he was assaulted (Metropolitan Police/PA)

He died on December 20 2017 and a post-mortem examination gave the cause of death as a head injury.

Antunes was eventually identified after detectives released CCTV.

He will be sentenced at the Old Bailey in February.