Put the cake into a 2.4-litre/4pt glass serving bowl. Mix the wine with 2 tablespoons of the cordial, and pour over the cake.
Dot the blueberry conserve over the cake, then pour the custard on top. Whip the cream into soft peaks, then fold in the remaining cordial and half of the blueberries. Add to the trifle.
Cover and chill overnight. Scatter with the nuts and remaining blueberries before serving.