This is an old family recipe that I've been making for years and even my children are helping me make it now. I've tweaked it, to make the base gluten free but if not, use normal ginger biscuits and I often make the topping on its own and serve with mini meringues.
I used a small size tub of cream from any of the main supermarkets but since they've all changed the size of their packaging, I tried guessing but the topping didn't set. The Elmlea™ size is perfect.
You can use either whipping cream or double, it works with both but is that bit richer with the double cream.