If you’ve got to the age when reading glasses are a part of your life, you have a handy little trick to impress your smug, better-sighted tramping counterparts who have forgotten their matches and lighter.

If the sun’s shining and a fire needs starting, assume your best James Bond pose, whip off those reading specs, and say: “Outta my way, two-eyes; I’ll show you how this baby’s done.”

Then, remaining in character at all times, follow these steps:

1. Collect a small ball of tinder – dry leaves and grass scrunched together
2. Point the lens of your glasses to the part of tinder facing the sun. Make the focal point as small and round as possible and hold it in the same spot for maximum intensity
3. With any luck, the tinder should start smoking. Keep the focal point in the same place until the tinder’s smouldering on its own
4. Blow gently into the tinder to intensify the flames
5. If you’re not having much luck, rub water onto the lens to strengthen the magnification. Or, if you’re really desperate, remove one lens and hold it behind the other lens to double magnification.