Put the redcurrants, blackcurrants and white currants in a pan with the caster sugar. Bring to a simmer over a low heat and cook for 10 minutes. Stir in the blackberries and raspberries, remove from the heat and leave to cool. The mix will be very liquid.
You can make individual puddings in dariole moulds, but this is really just a piece of presentational nicety. Line a pudding basin wi