A police investigation has been launched after the convoy escorting the Duke and Duchess of Cambridge collided with a pensioner.
The 83 year old is in hospital and is in a serious condition.
William and Kate are said to be "concerned and saddened" by the accident and have sent flowers.
It appears the lady was crossing the road when the accident happened.
She’s been named as Irene Mayor.
It’s not known at this stage who was at fault but the pensioner’s injuries are substantial.
William and Kate have written a personal message to her and have told their staff that they want to be kept informed of her recovery.
They’ve already been in touch with the pensioner’s family.
Members of the Royal Family always travel with a police escort.
The police outriders alternate the position around the main cars so that one bike is always ahead of the convoy to stop traffic.
The motorcycle at the very front of the convoy is thought to be the one which collided with Mrs Mayor.
The collision happened in an area of West London called East Sheen.
The speed with which William and Kate have been in touch with the pensioner and her family contrasts with the crash involving the Duke of Edinburgh in Sandringham earlier this year.
Prince Philip and his aides were criticised for leaving the scene too quickly and for failing to check on the well-being of those in the car he had hit.
William and Kate did not see the accident at the time and their police teams decided to keep driving to Windsor while others officers stayed at the scene to deal with the accident.
A royal aide from Kensington Palace has also met with the victim’s family.
The Independent Office for Police Conduct (IOPC), which is investigating the accident 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 enquiries as a witness.
"Our immediate thoughts are with the injured woman and her family and those affected by the incident."