Walkers' crisps ads have dominated our screens seemingly continuously for as long as I can remember. Has Gary Lineker now been promoting Walkers crisps for longer than he played football?

But while the crisps giant has spent more than double its nearest competitor on television and press advertising so far this year, in the past four weeks its weight of advertising has fallen.

Its most recent campaign, Do Us A Flavour, which asked the public to invent new crisp flavours, went off air recently and in the four weeks to 19 October it spent 66% less than in the same period in 2007.

Meanwhile, as Walkers perhaps puts the finishing touches to its new flavours, which it is sure to advertise, its rivals increased their activity. Pringles has jumped in with a new range - Pringles Select. Promising 'select ingredients combined for sophisticated flavours', its advertising focuses on new varieties such as Spicy Szechuan Barbecue and Sundried Tomato With Basil.

Promoting this collection, Pringles' spend has rocketed by more than 1,000% compared with last year. Indeed it has spent almost half of this year's advertising budget so far in the four weeks to 19 October alone.

Kettle Crisps also came back with a campaign that seems to work well. It was first aired in October 2007 and is a simple-enough concept - people on the street talking about their favourite flavours and how they like the fact they contain no artificial ingredients. Kettle recycled this series last month, with a spend up 255% year-on-year.

While Walkers, Pringles and Kettle have focused on flavour and ingredients, Ryvita and Unilever have been promoting their potentially healthier non-potato-based alternatives to crisps.

Ryvita has been advertising its new Limbo snack promising '90% less fat than regular crisps' because they are baked not fried.

The message is delivered, with a certain self-deprecating humour, by Fern 'gastric band' Britton.

Advertising also kicked off for another variant on the traditional potato crisp - Marmite Rice Cakes. Unilever spent more than £60,000 in press advertising using the ­parent brand's long-running 'love or hate' message.