Set aside 100g/3½oz each of raspberries and blackberries for decoration. Mix together the remaining berries. Bruise 200g/7oz of the remaining berries with a fork and stir through the basil. Set aside.
Crush the remaining berries and pass through a fine sieve. Reserve the juice and discard the pulp.
Grease 2 dariole moulds with a little oil and line with cling film (leave enough overhang to cover the top later).
Remove the crusts from the bread and discard. Cut out 2 circles to fit the bottom of the moulds and 2 circles to fit the top of the moulds. Cut the rest into rectangles to line the sides of the moulds.
Dip the small circles of bread in the reserved juice and push into the bottom of the moulds, dip the rectangles into the juice and press firmly around the edges, taking care not to leave any gaps.
Half fill the moulds with the crushed berries, add a tablespoon of cream and top with any remaining berries. Dip the larger circle in the juice and place on top. Cover in cling film and press down firmly. Chill until ready to serve.
To make a caramel, heat the sugar in a large non-stick pan until golden-brown. Use a spoon to quickly drizzle the caramel over a knife-sharpening steel (CAUTION: sugar gets very hot). Pull the strands of caramel together to make a sugar ball. Repeat to make a second sugar ball.
Turn out the summer puddings from the moulds, remove the cling film and put onto plates. Spoon over any remaining juice, decorate with the reserved berries and serve with a spoonful of clotted cream and a sugar ball.