A huge bang and ferocious fireball filled the garden as Oliver Lewis went up in flames yards from his wife.

The 31-year-old IT worker, from Saundersfoot, was outside burning garden waste in his incinerator when the petrol he was using exploded.

Once the fire was extinguished his wife Frances, 32, could immediately see her husband’s left forearm and hand were badly burnt.

It was then she remembered a British Red Cross first aid leaflet that dropped through her letterbox a few days earlier.

Frances said: “On so many occasions I have got a leaflet in the post and binned it without reading it, but I’ll be forever thankful for the first aid information that popped through my post-box that day.

“It was just a small Red Cross booklet, but the back of it contained information on how to treat burns. What are the chances?

“I remember thinking at the time that it was pretty useful information. Little did I know I’d rely on it just a few days later.”

Remembering the advice, Frances immediately put her husband’s burn under cold running water. Oliver was struggling to stay conscious because of the pain so she grabbed the booklet to check she was treating him correctly.

She said: “In such a stressful situation it is hard to think clearly, but having that knowledge and information to hand calmed me down and gave me the confidence that I was doing the right thing. Knowing a bit of first aid goes such a long way in an emergency and the Red Cross leaflet proved invaluable to me.”

Oliver spent a week on a burns unit in Morriston Hospital, Swansea, and two days in intensive care, but his arm is now on the mend.

He has regained feeling in his arm and the new skin has grown back, although he has to keep it out of the sun for the next two years.

British Red Cross first aid trainer Tracey Taylor said: “Frances’ quick actions meant that she treated her husband’s burns in exactly the right way and it’s great to hear that she had the confidence to help. We would encourage everyone to learn first aid; it’s simple to learn and easy to remember in an emergency and you never know when you will need it.”

Red Cross first aid advice on how to treat a burn:

1) Cool the burn under cold running water for at least 10 minutes.

2) After the burn has cooled, cover it with cling film or a clean plastic bag.

3) If necessary, call 999 or get somebody else to do it.

Visit www.redcross.org.uk/What-we-do/First-aid for more first aid advice, to find a course near you or to download the British Red Cross first aid app to your phone.