This is really a no-cook bread pudding for summer!
Pick through the blueberries removing any leaves or stems. Place the berries and sugar and water in a medium-sized heavy bottomed saucepan and cook gently for 10 minutes.
In the meantime, remove the crusts from the bread, and spread each slice lightly with softened butter. Sprinkle the buttered bread with cinnamon.
Arrange the berries and bread in alternate layers in a bread pan. Chill overnight. Serve with lightly whipped cream.