Sir Christopher Meyer, 74, was left with injuries to his eye, nose and lip after being beaten by two youths.

His wife, Baroness Catherine Meyer, told The Times that he had been taking the Tube home when he was attacked.

The British Transport Police confirmed the attack took place at Victoria tube station at around 2:45pm on Wednesday.  

He was admitted to St Mary’s Hospital in Paddington following the attack. 

A photo published in the newspaper shows the former ambassador in a hospital bed with his eyes closed and his face covered in blood.

His wife said: “He looks terrible. His left eye is like a golf ball and bleeding, the nose looks like it could be broken.”

She said her husband did not remember the attack, adding: “The first thing he remembers is the police.

“I’m absolutely shocked by the level of the brutality. They really beat him,” she said.

She said that at first she thought the attack was politically motivated as he is “opinionated” but the police have told her that the assailants were more likely to have been trying to rob him. 

She added: “Nothing was taken, but the Transport Police intervened quickly.”

The attack came the day before Donald Trump’s official visit to the UK. Sir Christopher had been expecting to provide commentary and do TV appearances during the visit.

He has called for the UK to engage with the US president while he is here. 

Americans in London have been warned by the US embassy to keep a low profile during the visit in case protests against him turn violent.

Police from nearly every force have been called up for Trump’s arrival, as demonstrators prepare to protest. It will be the biggest police operation since the 2011 riots. 

Sir Christopher served as the UK ambassador to the US from 1997 to 2003.

He was also ambassador
 to Germany in 1997 and was the government spokesman
 and chief press secretary to then Prime Minister John
 Major from
 1994 to 1996.