 BORN under a bad sign. That's what bluesman albert King sang in the late 1960s and it's what I'm singing now. If it wasn't for bad luck, I wouldn't have no luck at all. This is what happens when you try to do the right thing. If I'd anticipated embarking on a home-made damson ice cream extravaganza would result in such a bout of melancholy I'd have steered clear.  I have a damson tree in my garden. Every year it is weighed down by hundreds of juicy purple fruit. It'd be such a shame to waste them, so I end up spending hours cooking then forcing the darn things through a colander to get rid of the stones and skins. This brow-furrowing, messy activity formed stage one in the ice cream fiasco. Next came the sugar syrup. It solidified in the pan. Next the custard came close to scrambling. Then the piece de resistance. Mr Green knocked the brand new ice cream maker off the worktop, smashing the lid and reducing the two mixing arms to one. admit defeat? Never. I watched as the lone arm limped round the bowl, creating an icy damson delight. It was a bittersweet reminder that the green way is not always the easy way.  The average Brit gets through nine litres of ice cream every year. There are more than 