Put the rhubarb, root ginger, sugar and white wine in a pan, bring to the boil and simmer on a low heat for 4-5 mins until the rhubarb has softened. Remove from the heat and set aside to cool.
In another bowl, whisk the lactose free double cream and icing sugar to soft peaks. Remove 4 tbsp cooled rhubarb and mash with a fork, then fold into the cream mixture.
Divide the rest of the poached rhubarb between 4 glasses, reserving a bit. Spoon over the cream mixture, then top with a few pieces of crystallised ginger and the rest of the rhubarb. Can be chilled for several hours before serving.