"I approached them to see what was going on and to see if they needed help, and realised that she was giving birth."
He called through to make sure an ambulance was on its way, and went to grab a first aid kit out of the patrol car, Mr McCollum said.
"When I got back she had given birth into the father's arms. I just asked if the baby was breathing and well and they said that it was. The ambulance arrived shortly afterwards."
Mr McCollum praised the baby's father for his patience and hard work.
"Having had the training I was prepared to help, but the father did a pretty good job and obviously the baby was healthy and well.
"I think what I've done has been blown out of proportion ... the father, he was right there. If he wasn't there I would have absolutely got in and helped but he's the one that did all the work."
A hospital spokesman said the woman and her baby would be discharged from hospital today.