Following the Lowe heads up at Endicotts, I've spotted they have the Dutch wool blankets. I can reccomend these for serious use and amongst the things I have done with these blankets is the fabrication of a bush shirt including hood. The interesting thing about these blankets is that they seem completely immune for shrinking and 'felting' (if that's the correct expression?).
http://www.endicotts.co.uk/product_info.php?products_id=1872
http://www.endicotts.co.uk/product_info.php?products_id=1872