AT LEAST it was an improvement on the chain-saw that Santa brought the previous year. Quieter and safer, too. And the Nintendo Game Boy coveted by Kate Bevis (593 4 , mother of six, grandmother of seven), which appeared under the Christmas tree last year, could be played with in the comfort of the living room, rather than having to nip down the garden to lop off a few branches.

But then the family discovered even Mario, the Brooklyn plumber, and his pals had their drawbacks. The repetitive tunes signalling success, or more likely, failure, for instance. (The stereo headphones were not to Kate's liking.)

This grey-haired, matronly figure - an Oxford history graduate and Church of England lay reader - had been sucked into computer-game land and found the landscape every bit as compelling as did the younger family members.

That's how most of the 'battling grannies', as they were dubbed by one commentator, became hooked. The problem for some, such as Joan Thornley, 74, is that their 'habit' soon outstripped that of children or grandchildren who moved on to more interesting pursuits.

'We sit down and say we are not going to play it tonight, we'll go to bed early instead,' says Joan, her husband, Les, 70, nodding in the background. 'Then it's 'OK, we'll just have half-an-hour', and you instantly forget the time. The latest was 3am. My daughter would go mad if she knew.

'At least we've cut down. But it's hard. You pick it up and each time you think 'I must do it. I must get a better score'.'

Perched on the sofa of their Alsager home near Stoke-on- Trent, the addiction of the dogfighting duo is plain as they battle it out for several rounds.

Behind her large specs, Joan's face is a mask of concentration. Les, too, peers unblinkingly at the telly screen. On this almost surreal scene the parrot in the corner stares down impassively as Joan's toes curl and shoeless feet splay and twitch rhythmically while the console cradled in both hands twists and jolts in an effort to influence the action on screen.

As the pace of the game reaches its crescendo, defeat strikes again. 'Oh blast. I'm ashamed of my performance,' she says, without a sideways glance. 'Now then, play properly missus . . .' And off they go again in another round of Tetris, 'grandad', as she calls him, playing on an easier level.

'Some people think we're mad; a couple of silly old crows,' she says, putting the console down for a moment. 'Computer games. Computer games. Aren't they for kids? Some of the children think it's funny. But they come to the door and ask to swap games.'

Samantha, 13, the granddaughter who lives with them and won the machine in a breakfast cereal competition ('the second prize was a year's supply of Shredded Wheat'), is quite an expert. But she has graduated from Game Boys to real boys.

Kate Bevis's youngest children are at university, but during the holidays she has to unplug her hand-held machine between sessions to prevent them obliterating her last position once she sets it aside.

'I only allow myself three games at a time,' she says, sitting in her rambling Victorian semi in Barnet, north London. 'It's the most appalling waste of time and not even relaxing. It's fun for a very short time. But by the fourth time Mario has been eaten by some monster you lose your temper.

'But I'm totally addicted. With an addiction, though, you're supposed to get some simple pleasure. Not with this. It's very, very irritating. I even dream about it sometimes. And I certainly think about how I'm going to overcome the next hurdle when I get stuck. But while I can figure it out, I sometimes don't have to skill to make him do what's needed. That's the advantage the children have.'

Her children caused the problem by giving it to her, but her curiosity was first aroused when she noticed her fidgety choirboys had inexplicably become quiet. 'They had gleaming faces all of a sudden. Then I discovered that they were all playing their Nintendos with the sound turned down. I wanted a go, too.'

Now they're all at it. 'I even threatened to take mine along for the anthem,' she says, grinning. But then she becomes serious. 'Don't write anything that'll make me look like a loony or I'll never be allowed to take another funeral.'