MARKS & Spencer sells more than four million pairs of slippers each year -- but they have to pass the 'Burnley test' before reaching the shelves of stores throughout the country .

A panel of 12 women, aged from 27 to 96, examine the new styles and give their verdict before they are accepted by the famous high street store.

The panel, which has just completed its first year, is unique and includes three generations of the same family: Ethel Altham, 96, her daughter Christine Pickles and granddaughter Lesley Pickles, who live together in Cliviger.

Kerry Divall, Marks & Spencer product manager for women's slippers said footwear bosses came up with the idea and that as well as passing all sorts of checks, the slippers had to win over customers.

She said: "The company attributes its success to listening to what customers want.

"The panel of slipper-buyers made up of customers of various ages keeps the company on the right track."

The panel tests are regarded as a key to knowing what women of all ages will want to buy.

Slippers are not just for Christmas and the panel meets to examine the different seasons' new products in the boardroom at Lambert Howarth and Global in Healeywood Road, Burnley.

Lambert Howarth, a supplier to Marks and Spencer for 90 years, have made more than 50 million pairs of slippers in the last 34 years at their manufacturing branch in Ronaldsway, Isle of Man

Ethel said: "I love wearing slippers so was ideal for the job."

Lesley, 33, a lab technician at Lambert Howarth, said the panel carried out slip tests on the footwear as well as advising on value for money, design, colour and comfort.

There were widely different styles of different ages from young people right up to people of her grandmother's age.

Lesley said: "Some styles I would not pick for myself but which I might choose for my mum or grandmum, who fell recently and broke her hip.

"With that in mind I would select something more substantial with support in the heel."

Slippers are striding purposely back into fashion. A staggering 1.6 million will be sold by Marks & Spencer in the run-up to Christmas.

With the approval of Ethel and other members of the Burnley panel, young women will be snapping up suede clogs while men are discarding their trainers in the house for mules, the current best seller in the men's range.

Kerry commented: "The very idea that slippers are unfashionable is long out of date. We sell large numbers of of our suede clogs each week."

And further change is afoot. Among the designs approved by the panel and destined to arrive in stores early next year is a new range of slippers with additional support for the jaded heel and instep.

One test that the panel members have to carry out is a wearer trial which involves repeatedly walking up and down stairs to demonstrate how slip proof is the footwear.