The hidden secret in the Italian Lelli Kelly girl's footwear range lies beneath the leather insole where a layer of material which will instantly convert perspiration into a gel-like substance has been inserted.

Lelli Kelly has coined the trade name Dryz to describe this substance and has developed as a point-of-sale aid to help potential customers test out its efficacy simply by adding water and watching the liquid convert to gel.

By Sonia Roberts.