Grandson George, aged four going on 40, is ready for school.

He will start at the village school in September, his uniform is on order and he has met some of the boys and girls who will be in his class. I remember so well the lurch in my tummy when my own children had their first day at school.

Ruth's best friend (they had been at nursery together) sobbed every day of the first half term. Ruth was more stoical, although she did cry once, telling me later that she had tried to push the tears back into her eyes. But it wasn't long before she loved her teachers and wanted to invite everyone in the class to her birthday party (I should cocoa; max six).

School was the beginning of the end of her parents being the most influential beings in her universe.

Soon, we were usurped by... just about everyone. Aged six, Ruth came home and informed me she now knew the REAL facts of life as opposed to the ones I had told her (just enough, not too much). Despite being 99.99 recurring per cent certain my facts were correct, Ruth preferred to believe a girl in her class whose wildly inaccurate account of human reproduction involved gooseberry bushes and shaking hands with a boy.

I went over the whole thing again. My daughter listened intently and when she came home from school the following day said she had run my version by the girl in her class but they were doubtful I was right.

Two years later, Mark started school and I soon realised I should have pointed out to him the risks of reckless behaviour such as clambering to the top of the climbing frame and jumping off.

'Does he do that sort of thing often?' asked his class teacher, still in shock.

He hadn't. I expect he was testing the boundaries of his new, bigger world, the one without omnipotent and omnipresent parents.

Later in their primary school years Ruth and Mark began to compare us unfavourably with other parents... the ones who let their children stay up until midnight, who gave them £5-a-week pocket money, who let them drink wine. Funny, but I never did meet any of those parents.

Our infallibility began to ebb away as soon as the kids went to school, and 10 years later it had disappeared altogether.

But at least the misconceptions and dangers faded.

As grandparents we happily acknowledge George already knows best. He likes to know about things and when he doesn't quite understand something, he creates a scenario of his own.

The children's DVD we play in the car includes some pretty ancient songs – George is particularly fond of the Morecambe and Wise classic 'Boom Oo Yata-ta-ta'. Two-year-old Wil likes to join in with: 'Trump, trump, trump,' which is not approbation for the US president but a chorus in 'Nelly the Elephant', a song about a pachyderm who escapes from the circus.

Another of the numbers is 'Seven Little Girls (sitting in the back seat)'. The lyrics reveal the seven little girls of the title are in the back seat 'kissin' and a'huggin with Fred'. George doesn't fully twig what this might be about so he has devised his own explanation... in which Fred is the daddy of seven little girls. The Scaffold song with the line: 'Thank you very much for the Aintree Iron,' has been re-worked to: 'Thank you very much for the empty lion.'

Last week grandpa took the two boys to the local zoo, at Linton, where they have a season ticket. On this occasion, George airily announced he was only going to visit animals beginning with 'T' – the tapirs, tortoises, toucans and, as an afterthought, the tigers. For the sake of getting their season's money's worth, I trust he is not going through the alphabet a letter at a time because U, V, W, X, Y and Z won't take long... not unless they acquire wildebeest and walruses.

At the village fete, a few days later, George continued the theme by having his face painted as a turtle. Wil wanted to be a turtle too. He loves his big brother.