Mix all the ingredients together in a medium saucepan. Cook over medium low heat for 15 to 20 minutes, until the fruits are completely soft, stirring occasionally. Remove from heat and set aside to cool down.
Place both types of flour in a large mixing bowl with the butter, sugar, and salt. Use your fingers to rub the mixture into a bread crumb like texture. Then stir in the walnuts.
Spread on a baking sheet lined with parchment paper and place in the oven for 15 to 20 minutes, until dry and cooked through. Remove and leave to cool.
Place all the ingredients in a large mixing bowl and whisk soft peaks, take care not to over whip (it is quite thick to start with, so it shouldn't take more then 30 seconds)
Spoon one third of the crumble into the bottom of a medium glass. Cover with two thirds of the fruit, then two thirds of the cream. Another one third of the crumble goes on top of this, followed by the remaining fruit and then cream.
Scatter the remaining crumble on top just before serving. Serve at once, or chill for a few hours.