Place the strawberry jelly crystals in the heatproof jug and add 285ml (1/2 pint) of boiling water. Stir until all the jelly crystals have dissolved completely. Add 285ml (1/2 pint) cold water and stir. Leave to cool, then divide between 6 x 350ml tall glasses.
Divide the sliced strawberries between the glasses, placing them in the liquid strawberry jelly. Place in the fridge for 2 hours until set firmly.
Place the orange jelly crystals in the heatproof jug and add 285ml (1/2 pint) of boiling water. Stir until all the jelly crystals have dissolved completely. Add 285ml (1/2 pint) cold water and stir. Leave to cool, then gently pour over the firmly set strawberry jelly in the glasses.
Divide the well-drained mandarin orange segments between the glasses, placing them in the liquid orange jelly. Place in the fridge for 2 hours until firmly set.
Place the blackcurrant jelly layer in the heatproof jug and add 285ml (1/2 pint) of boiling water. Stir until all the jelly crystals have dissolved completely. Add 285ml (1/2 pint) cold water and stir. Leave to cool, then gently pour over the firmly set orange jelly in the glasses.
Divide the blueberries between the glasses, placing them in the liquid blackcurrant jelly. Place in the fridge for 2 hours until firmly set. Serve alone or with a swirl of reduced-fat aerosol cream or biscuit, if wished.