This was the pinnacle of the fire-raising career that lasted into my early teens. How Andy and I made it to adulthood is anyone’s guess. We were always setting fire to things or blowing them up.

For example, Andy and I discovered that an air bomb firework, lit and then put upside down in a milk bottle, made a pretty effective fragmentation bomb capable of severely damaging a containment vessel such as an old tea chest. We developed firearms that would launch penny bangers (firecrackers) a good 25 or 30 yards. Ever been snowballing and seen the big lads catch your snowball? They tend not to do that if you plant a lit penny banger in it, wait till it’s fizzing, and chuck it then. Even big lads get startled by an explosion they aren’t expecting. In their hands.

We also perfected the technique of using rockets to drop lighted bangers into the back gardens of people we didn’t like. I’ll not tell you how, but it can be done.

Making gunpowder? Oh yes, done that. It’s not as easy as it sounds. You can have all the ingredients in the correct proportions, and it will burn slowly and give off acrid yellow smoke. Other times it’s so bloody unstable you only just have time to clear ground zero and get hull down over the horizon before things go off.

I must point out that the intention was never wanton destruction of property, and we never tied fireworks to cats or anything like that. It was all simple ‘make a bang’ stuff. Model aeroplanes, model cars, that sort of affair. Though it was always fun to lob a weighted banger down a storm drain when the local bully was about to saunter past. As long as the banger is fizzing, it will go off underwater, and create quite a splash up top.

One of our finest inventions was the exploding squash ball. I could probably make one now using things I find in your kitchen or utility room. Let me loose in your medicine cabinet and I’ll virtually guarantee it. I might need a coffee mill too. And a catapult.

On another occasion we lit a fire in the back yard, and we set it on a metal vent to increase the airflow under the fire. This worked so well that in the resulting inferno the metal grid expanded in the heat and nearly pushed a wall over. We got in trouble about that.

So setting fire to Andy. How did this come about? We were fooling about one day, and had a small fire going. The twigs were a bit damp, and it wasn’t burning too well. Now I just happened to have on my person an old washing up liquid bottle, which was half full of methylated spirit, and I decided it would be a good idea to squirt this onto the guttering flames.

You may have done something similar with a recalcitrant charcoal barbecue. People always tell you not to, but keep your wits about you and it’s easy. Same principle applies as to firebreathing. Keep the stream moving too fast for the flame front to flash back. Barbie fluid is OK for this, since it won’t actually burn very easily in a liquid state. In technical terms, the flashpoint is too high, and it will only burn as a vapour released from a porous substrate. Just don’t try it with petrol. It will end in tears.

Methylated spirit on the other hand… has a low flashpoint, and the vapour is pretty inflammable too. So if the flame front runs up a stream of vapour and into a confined space, things will get very hot, and just as in a car engine, things will expand quite vigorously. In a car engine, this drives the piston down with considerable force. In a washing up liquid bottle, things aren’t quite as robust.

There was a quiet ‘wuff,’ then the bottle swelled up in my hands to about twice the normal diameter. The nozzle disgorged a stream of burning meths shortly before exploding out under the excess pressure. And Andy caught the full blast all over his jeans.

We managed to beat out the flames before any material or fleshly damage was done, but my mum had witnessed the whole episode from an upstairs window. She wasn’t pleased.

Even then Andy and I couldn’t leave it alone. We’d sit at the back of maths classes trying to work out how to build a rocket-powered car based on the meths-in-a-washing up-liquid-bottle.