“IT’S probably coming from your air conditioning unit,” said my brother-in-law. “I’m sure the car’s perfectly safe to drive.”

But I wasn’t so certain as I stared, with dismay, at the stream of water that had suddenly appeared underneath the car.

Four of us were on our way back from a wedding in Cardiff and had stopped for a coffee at a layby about five miles this side of Devizes.

I had been a little anxious about the car ever since lifting the bonnet a few days previously and discovering, to my horror, that the cap to the expansion tank had somehow fallen off and that the water level was alarmingly low.

The stream trickling into the grass verge of the layby now seemed pretty conclusive evidence that I hadn’t got away with it as I’d hoped and that something was very wrong.

Luckily, we had mobile phones with us so were able to contact the RAC, who said they’d do everything they could to be with us in an hour and a half.

We waited. And waited.

Presently the telephone rang and the RAC warned us that there’d be a delay because they were being rushed off their feet.

But it was a gloriously sunny afternoon and the clocks had gone back during the night so we had an extra hour at our disposal.

In addition, we had a couple of flasks of coffee, a store of chocolate biscuits, a newspaper and crosswords.

So we drank the coffee, ate the biscuits, read the newspaper, tackled the crosswords, chatted, dozed and took it in turns to stretch our legs until the RAC patrol turned up.

I tell you all this to point up a moral – and to pass on a bit of wisdom.

The moral is embedded in an old joke (I think it’s Jewish) that if you want to give God a good laugh you tell him your plans.

In this case our plans for the afternoon had been well and truly jettisoned.

The wisdom is that of GK Chesterton, who wrote a lot of sense about the nature of happiness.

The thrust of his argument is that you can often enjoy yourself in the most unlikely circumstances if only you put your mind to it.

His advice goes along these lines: that to the best of your ability, and within reason, you should attempt to enjoy experiences as they come along, to make the most of them and turn the negatives into positives.

“You know, I’ve really enjoyed myself this afternoon,” said my brother-in-law as we climbed back into the car and continued on our journey to Bournemouth.

“It’s been nice just to have a little time to unwind.”

Here, indeed, was living proof of the truth in Chesterton’s wisdom.

But what impressed me even more was the way he resisted the temptation to say “I told you so” when the RAC man made his report.

“The water’s coming from your air conditioning unit,” he said.

“The car’s perfectly safe to drive.”