But no one ever paused to consider the wider consequences of all this innovation. Who, in 1925, would have predicted that television would turn men into fat, mindless lager-drinkers? Did Orville Wright imagine for one moment that his aeroplane would be the cause of women aged 18 to 30 giving birth to babies called Fernando? And did it occur to anyone that e-mail could make it so frighteningly easy to click the wrong button and instantaneously inform your boss that you’ve spent the morning daydreaming about massaging a loved one with Haagen-Dazs?

All this was brought home to me recently because Sarah’s headteacher, Pedantic Pete, has already had to issue a codicil to the Home-School Agreement. Appended to the list of “disruptive activities” in which we have undertaken not to indulge is the carrying of mobile phones onto school premises.

But, I hear ou ask, how can a child of school age possess a mobile? Didn’t you have to be over 18 to sign the line-rental agreement? Not anymore, thanks to the prepaid card system! Now anyone who knows how to use a scratch-card can buy a phone, punch in a few numbers from the card and bingo! a topped-up phone ready to be left in the bottom of a school bag to go off during lessons.

Did the techno brat behind prepaid cards ever stop to question what he was doing? No. He thought: “What single activity is the entire population capable of?” Answer: scratch-cards. Okay, let’s make that the method of payment.

Did he realise this might well put 30 phones in every classroom in the land? No. Did he realise that this was denying parents like me an easy answer to children who nag us for mobiles “Sorry, love, you’ve got to be 18.” No. Did he realise that pre-paid mobiles would finally put me in agreement with Pedantic Pete? No.

But then neither did I. That she and I should be on the same side for once was a consequence that no one could have predicted.