One thing everyone agrees on about May 16 is that it was a perfect early summer day, the first really warm day of the year.

The sunshine brought everyone out and sent thousands heading for the beach and wide open spaces.

Dr Marianne Jackson, an A&E consultant, and her family were among them. In the mid-afternoon Marianne loaded bikes for daughters Grace, ten, and Maisie, six, on to the car and headed for Preston Park, not far from her Brighton home. Husband Michael and son Steven, eight, had gone on ahead.

Just as they arrived at the park, Dr Jackson's mobile phone rang. As a SIMCAS (Sussex and Surrey Immediate Medical Care Scheme) emergency doctor, she is used to being called at a moment's notice to provide critical care at the scene of an accident. Her role is voluntary yet her expertise can make the difference between life and death.

SIMCAS doctors are called to incidents ranging from cliff rescues and floods to people trapped in fires. Most calls are to road accidents though none can compare to the scene she was about to encounter.

Dr Jackson said: "The accident had just happened. All ambulance control could tell me at that stage was it was a report of a car on fire. Often the information they are able to give is very limited so we never know quite what we are going to."

Dr Jackson had not yet met up with her husband so, spotting another mother from her children's school, she asked her to look after the girls until he arrived.

Then she jumped into her car, switched on her blue light and drove to Pyecombe.

"When I arrived it was chaos. The fire brigade was there and an ambulance had just arrived. I remember thinking that car has been cut in two, how bizarre'. I think I just went on to automatic pilot.

"I walked towards the Land Rover where people were trapped and ascertained the person who most needed help was the little boy, Marcus, who had been in the back.

"By this time he was out of the car and on the ground. He was very sick and barely breathing. His heart stopped soon after I arrived and we resuscitated him.

"We got him into an ambulance and whizzed him to hospital doing as much as we could for him on the way. I think I knew he was going to die. At that stage we were not sure the dad was going to make it either.

"I stayed at the hospital for a good while longer but there was nothing else I could do. Even at that stage I don't think we knew how many others had died."

That evening Dr Jackson went home, tucked her children up in bed and reflected on the tragedy.

She said: "It is always unpleasant when you lose a patient.

"It is really dreadful when it is a child and as a mother it has an even stronger effect.

"That night I hugged my children and thought how lucky I was."

As an A&E consultant at Worthing General Hospital, Dr Jackson can confront death on a daily but it never becomes just part of the job.

She said: "Sometimes I have to go into my office and have a little weep. You get involved.

"Being a SIMCAS doctor is different because you don't know the patient and usually you are there on your own.

"I'm not hard. When you have to be strong for others you just are.

"The really awful part of my job is telling a parent their child is going to die or that they have died.

"In this case I didn't have to do that so in many ways I was shielded from the emotional side.

"I have replayed the incident in my mind a lot. You always want to do more and think you should have done more, no matter how many people tell you there is nothing more you could have done.

"Whenever I drive past the spot I look at the flowers and feel really sad for the young lives lost."