From London to Inverness, over the past two years the UK has contracted a serious case of knitting fever as a series of “guerrilla knitting” or “knitting graffiti” projects have popped up around the country.

Last year a signpost in Edinburgh's Bristo Square was spotted wearing a thick woolly jumper, meanwhile further north in October 2009 the Skye Bridge became the canvas, which at 500m long was the largest guerrilla knitting project Scotland had ever seen.

The Stitches on the Bridge project was launched to celebrate Scotland’s Homecoming year and attracted contributions from as far afield as China, the United States and Australia. The final piece stretched the entire length of the bridge.

Also under wraps were parts of Inverness city centre, which in September of last year saw a week-long publicly funded project to celebrate the regeneration of the city's Old Town. A series of locations were engulfed in scarlet knitting, with displays that included large pom-poms in the street, crocheted spiders' webs across alleyways and tombstones in an ancient graveyard covered with cosies.

More knitters hoping to the pull the wool over authorities eyes have been at work south of the border this year, with Leeds and Manchester both succumbing to the woollen warriors, and earlier this year Craft Northern Ireland yarnbombed Belfast as part of August Craft Month.

In honour of National Wool Week last week, those in the loop in London staged a yarnbombing event organised through Knit the City, a tight-knit group of enthusiasts headed by knitting celebrity Deadly Knitshade. Knitters created a flock of miniature sheep crossing the Thames at London Bridge.

Knit the City have staged a variety of guerrilla knitting events including putting a woollen cosy on a phone box in ParliamentSsquare and creating a 15 foot knitted spider web in a tunnel near Waterloo Station.

Yarn bombers are knitters, crocheters and textile artists who ‘tag' street furniture with uplifting woolly creations. This unique art form sees knitting being attached to large landmarks, such as bridges and statues, as well as more mundane objects commonly found around towns and cities in an attempt to bring colour and art to the streets.

Texas-born Magda Sayeg is the founder of one guerrilla knitting group, Knitta Please, and is widely credited as the first yarnbomber when she decided to find new and creative ways of using leftover material. Her recent achievements include a crochet-covered bus in Mexico, and tagging the Great Wall of China with knitting.

Knitting Guerilla enthusiasts claim that the movement has given a lifeline to a craft that was once considered old fashioned, and knits together traditional methods with contemporary ideas to make fresh and exciting artwork.

It has become something of a phenomenon, with artists and craftspeople throughout the world using knitted and crocheted materials to add splashes of colour and texture to surroundings and put a different spin on familiar landmarks and locations.

National Wool Week, which ran from October 11th -17th, was a key aspect of HRH The Prince of Wales’ cross-industry initiative called The Campaign for Wool, which he launched in January this year. You can watch a video of this campaign launch below.

The project aims to promote the versatility and sustainability of this natural fibre with the intention of increasing demand, which has been declining recently. The campaign is supported by many high street names including Debenhams, John Lewis and M&S.

National Wool Week may be over, but with the cold nights drawing in and this winter set to be a cold one the guerrilla knitters may well strike again, leaving us to ask whodunknit..?