Sitting at my breakfast table, I was disconcerted to see on my cereal packet a recipe for "Fruit and fibre fish bake". Poor, desperate home economist!

Admittedly, the cereal was an own-label one, but it did remind me of the extremes that marketers will go to squeeze the last drop of turnover out of their brands. They have little choice. Unthinking management heroics reject any future scenario that is not based on growth and the recession makes it risky to build new brands.

So marketers are constantly on the lookout for new users, and new types of usage, introducing to their brands new product forms, new packaging, new flavours, new colours, new channels of distribution, new positionings. Frequently, they achieve the immediate growth in sales which they are seeking.

But at what cost? Too often apparent success proves to be a sort of "brand cancer" - an uncontrolled growth which ultimately prevents the original organ from functioning properly. Too often the proliferation is succeeded by loss of turnover, or brand share. Look at Spangles or Ski.

Every product seems to have an optimum size at which it is comfortable and effective. It has to be big enough to command and maintain its chosen network of distribution, and, if appropriate, to pay for advertising and promotional support. It has to be small enough to identify with particular needs and language of these people who constitute its prime target market.

The main message can be lost in the flurry of activity designed to pick up smaller and smaller sub-sets of new users. …