Put the water and granulated sugar in a saucepan and heat gently,
stirring, until the sugar has dissolved. Bring to the boil and simmer for
5 minutes. Add the peaches, cover and simmer for 5 minutes until tender.
Remove the peaches from the syrup and transfer them to a large serving
dish. Mix together the cream and yoghurt and spread over the peaches. Mix
together the demerara and soft brown sugars and sprinkle them thickly over
the cream. Cover and chill for several hours until the sugar melts on the
top.