Heat the oven to 180C/160C fan/gas 4. Toss the berries, cornflour and brown sugar together in a large bowl (if you’re using very tart berries, you can add a little more sugar, if you like). Tip into a pie or baking dish (ours was 22 x 22cm).

Put the flour and a pinch of salt in a large bowl, and rub in the butter until the mixture resembles coarse breadcrumbs. Stir in the oats. Scatter the crumble mixture over the berries, then sprinkle over the demerara and bake for 55 mins-1 hr, or until the crumble is lightly golden and the fruit is bubbling at the edges. Serve warm with custard or clotted cream, if you like.