The ambulance service has explained why it took almost one hour to respond to a serious accident in the city centre, where a sign from Clarks fell on a woman's head.Paramedics were first called to Brigg Street at 2.05pm on April 6after a woman suffered a serious head injury when a sign fell from a shop front.

But a witness said an ambulance did not arrive until close to 3pm.

A spokesman for the service said the delay was caused by the information it received from the call. He explained: 'We received a call at 2.05pm on the April 6 to reports of a woman who had a head injury on Brigg Street, Norwich.

'The call was originally coded as a green call based on the information provided by the caller which requires an ambulance response within 30 minutes.

'Three more 999 calls were made and at the time of the final call at 2.41pm the patient's condition had deteriorated. The information provided by the caller deemed it a red call which requires a response of eight minutes of which we managed to arrive on scene at 2.50pm.' The woman, who is in her 20s, was taken to the Norfolk and Norwich University Hospital for further treatment. Clarks said it was investigating the incident as it happened outside its store.