From your link:
Clarence House said that the couple were unharmed in the incident on Regent Street, but onlookers said Camilla looked extremely shaken after the attack.
The Prime Minister, David Cameron, described the attack as ‘shocking and regrettable’.
One protester who witnessed the attack said: ‘We were headed up towards Regent Street and there didn’t seem to be a lot of police about and people were throwing things at shops.
‘Then out of nowhere came this car and when you looked into it you could clearly see Prince Charles and Camilla inside it looking incredibly confused.
‘We all stood there for a millisecond in stunned silence and then people started lunging towards the car from all sides. It all happened very quickly.’