Combine bananas with orange juice (this will help stop the banana from going brown).
Arrange the trifle sponges in the base of a serving bowl to form an even layer, cutting to size if necessary. Sprinkle the sponge with half the Cointreau. Pour half the vanilla custard evenly over the sponge. Layer with half the jelly, then half the bananas, strawberries and blueberries in the bowl. Repeat these layers starting with another layer of sponge, then cover and chill until serving.