Unless you have filled up your diary far in advance, a trip to the Edinburgh Fringe can be filled with off the cuff decisions as you find yourself with hands full of flyers and surrounded by walls of colourful posters advertising the multitude of shows on offer. And with so much going on, plans can change at the last minute and hidden gems may suddenly present themselves.   Picture the scene, after a few days escaping it under greyish skies and a ferocious wind, the heavens o