The day before soak the sultanas in brandy by placing in a small dish or espresso cup and covering with brandy.
Preheat the oven to 180 C / Gas 4.
Pan toast the almonds and set aside. Cut the pork fillet in half and then flatten out each half until it is the thickness of a pork escalope.
Drain the sultanas but retain the liquid. Season the pork with salt and pepper, divide the sultanas and almonds between each half.
Roll up (think Swiss Roll) and secure with string. Can be made ahead to this point and refrigerated until ready to cook.
Heat a frying pan with a little oil and pan fry the pork until browned and sealed. Cover and roll each fillet tightly with foil.
Bake in the preheated oven for about 40 minutes.
Remove from the oven. Carefully remove foil and string, Pour any meat juices into the fry pan. Add the reserved brandy soaking liquid and bring just to the boil. Add a knob of butter and cook for a minute. Slice the pork into 2 or 3 chunks per fillet and serve with the sauce (it won't make a lot - just enough to moisten) over the top.