THERE are grandparents everywhere. Until I became a grandmother myself, I didn't really notice them. They were invisible, just part of the landscape.

Now that I've become one of them I see them wherever I go. It's almost as if they're part of a secret society to which I now have the password, though I know it's just that I hadn't noticed them before.

I see them pushing babies round the supermarket, collecting toddlers from playgroup or nursery, meeting juniors from school, escorting reluctant teenagers.

Walk down any High Street in half term week and you realise that many families would fall apart without grandparents. They're the ones who take charge of the children while parents are working.

Visit any local attraction during the school holidays, and they're there, with grandchildren in tow. Walk past the swings, and they'll be watching while their grandchildren play.

They don't always have children with them of course. Sometimes the grandchildren live a long way away. But once you know what to look for you can still spot the grandparents.

They're the mature people who smile indulgently at harassed parents trying to cope with restless infants on buses and trains; the ones who don't mind a family with a child joining their table in a crowded cafe; the ones who rush to comfort a fallen toddler in the park.

Go into the toy department in any large store and there you'll see them - especially the grandmothers, those mature women lingering over the latest brightly-coloured plaything, fingering it longingly, reading the instructions with care, checking the age range for suitability. Or they'll be in the children's clothes section, swooping with delight on that pretty little dress or that bright sweat-top with its cheerful motif.

I know, because I've been that grandmother - and caught the eye of one or other of my fellow grans as I check the size of a tiny pair of trousers, try out a musical toy. We smile that knowing smile. We each know exactly what the other's doing, why we're there, what's uppermost in our mind. We're thinking, 'Wouldn't he/she love that!' or 'My goodness, they didn't have things like this when ours were small!'

We won't necessarily be buying. We may just be looking, planning, dreaming. But we will buy eventually, and we'll probably spend an unreasonably large amount.

A grandad said to me once: "The one thing I know about grandchildren - they keep you poor". Well, yes, in a way. But only because you choose to let them. After all, what are grandparents for, if not to spoil their grandchildren?

Take that toy puffin, spotted in a gift shop in Seahouses. All right, we know Jonah doesn't need any more soft toys. He's already got more than he knows what to do with. They come in useful at bedtime, because he can use them to try and summon his parents back to his bedside when he's supposed to be going to sleep, by shouting for 'Black Cat!' or 'Tiger!' or some other creature he claims is essential if he's to settle happily down for the night. But otherwise, he doesn't play with his cuddly toys very much. But the toy puffin was so cute, so soft and appealing, that his grandad, out for the day, couldn't resist it. Jonah loved it too.

"It's a penguin!" he exclaimed. We tried to explain and he got the name right in the end, but he's never seen a puffin, so I suspect he'll go on believing in his heart of hearts that it's a strange sort of penguin - at least until he's old enough to come with us on a boat to the Farne Islands to see puffins for himself, in all their comical appeal. We look forward to that day.

One thing you'll almost never see is a grudging, miserable grandparent who doesn't want to lavish time and money on the grandchildren. Because that's the thing about grandparents, or most of them anyway. They love doing it; they like nothing better than to play their role to the hilt. Just a short while ago they were simply older people whose children had flown the nest. All right, we enjoyed the freedom of our mature years, found plenty to do. But we were conscious too that we'd become part of that increasing yet almost invisible section of the population who are told we are a problem, a future burden on the nation's wage earners.

Then the grandchild arrives and life has a whole new dimension, a new purpose. To our children we're now an invaluable, willing support in times of crisis. And to our grandchildren? Well, we may still be invisible to most of the world, but we know we'll never be invisible to them.