The waiting time at a pavement incident is in proportion to the severity of the situation as reported by the bystander when they first made contact with the ambulance service. They triage calls based on information provided- although distressing the service have to prioritize based on life-threatening risks.
In this instance, if the message was an elderly person over 70 who was bleeding would have a higher response than someone of 50 in the same situation.
This may seem harsh but it is the reality of triage which is why sometimes many ambulances are backed up with people who could have arranged their own transport to hospital but often people think they will be seen quicker if they go by ambulance — but this is not the case- the same triage applies if someone arrives by ambulance or through the main door.