Royal crash: Elderly woman seriously injured after being hit by police motorbike escorting Prince William and Kate in London

The lady, who is in her 80s, is in a serious condition in hospital following the accident in Richmond, south-west London.

William and Kate were on their way to a ceremony in Windsor on Monday when a marked police motorbike in their convoy was involved in a collision with the woman on Upper Richmond Road.

She has been locally named as Irene Mayor and was taken to hospital in a critical condition, Scotland Yard has said.

The duke and duchess are ‘deeply concerned and saddened’ by what happened, Kensington Palace said. They are understood to have sent flowers.

The Independent Office for Police Conduct (IOPC) is investigating the circumstances of the collision which involved a motorcycle attached to the Royalty and Specialist Protection Command.

A witness told The Sun: ‘His bike hit her and she spun round, off her feet and fell badly on the floor.’

Her daughter Fiona told the newspaper the royal couple have offered to visit.

She added: ‘She's got lots of injuries. They are just keeping her stable at the moment.’

An IOPC spokesman said: ‘The woman, in her 80s, suffered serious injuries and was taken to a London hospital where she remains in a serious but stable condition.

‘In line with procedure, the Metropolitan Police Service referred the collision to the IOPC.

‘Our staff attended the scene of the incident and after careful consideration, we have launched an independent investigation.

‘The investigation is in its very early stages and the officer involved is assisting our inquiries as a witness.

‘Our immediate thoughts are with the injured woman and her family and those affected by the incident.’

Kensington Palace said: ‘The Duke and Duchess of Cambridge were deeply concerned and saddened to hear about the accident on Monday afternoon.

‘Their Royal Highnesses have sent their very best wishes to Irene and her family and will stay in touch throughout every stage of her recovery.’

The accident took place at around 12.50pm on Monday when the royal couple were on their way to Windsor for the St George's Chapel service commemorating the Order of the Garter.