Rub the butter and flour together in your fingers, till it goes like breadcrumbs.
Add the oats and sugar, and mix well.
Put the blueberries in a saucepan and put the heat on boiling setting. Use a wooden spoon to break up the blueberries and add the sugar. Once the blueberries have gone like purple syrup, add the tinned peach slices and mix well.
Put the peach and blueberry mixture into an oven proof dish (I aways use a casserole dish). Sprinkle the oat topping over the fruit.