Processors of leather for use in the fashion industry now have the potential to offer consumers leathers which will cling as tightly but stretch as readily as their own skin.   The idea of adding a stretch element to tanned animal skins was mooted at the last Premiere Vision of 2000 and spring 200l sees this adroit marriage of the natural and the technological go fully commercial. In fact, one week after Leather with Lycra had its official debut on the DuPont stand at the Paris textile fair it proved a show-stopper for both Lawrence Steele and Georges Rech on the Milan haute couture catwalks.