The first to arrive at the scene of the accident in which Mark Staddon, 33, died were were Marlborough GP Richard Hook and Simon Routh-Jones, Wiltshire's chief fire officer, both of whom were off-duty.
Police say Mr Staddon, of Bath Road, was walking along the A4 at Fyfield near his home on Monday at 7.20pm when he was in collision with a Jaguar car being driven towards Marlborough by a 59-year-old man.
Dr Hook and Mr Routh-Jones found Mr Staddon, who was the son of driving instructor Lavinia Staddon, unconscious and in cardiac arrest.
Both administered 'bystander CPR' until the emergency services arrived.
Dr Hook advised the ambulance service to call Swift Medics, a group of medical doctors who attend serious medical emergencies on a voluntary basis.
Three members of the team – doctors Jonathan Glover, Dan Bawden and James Mapstone – were at a meeting in Marlborough and were there ten minutes after the call.
Dr Jonathan Glover, of Swift Medics, said: “The pedestrian received the very best medical care under the circumstances – he had a full hospital-style resuscitation team until the arrival of the air ambulance.
“Sadly, his injuries were catastrophic.”
Medics administered CPR for 25 minutes until the Wiltshire Air Ambulance landed on the A4, but Mr Staddon was pronounced dead at the scene at around 8pm.
The A4 was closed for three and a half hours to allow police to investigate. Any witnesses are asked to call PC Ecclestone at Wiltshire Police on 101.