It's been three years since we first wrote about Knitta, the Montrose artistes who were pioneering the art of guerrilla knitting.Since then the phenomenon has spread worldwide, according to today's UK Telegraph."Knitters turn to graffiti artists with 'yarnbombing'" is the headline.You'll have to imagine hearing this in a plummy BBC accent:The phenomenon, called Yarnbombing, is thought to have originated in the US but knitters are now beginning to cover British streets in woollen 'tags'.Quite oft