We've taken to having brie and mango chutney sandwiches around here on occasion. I've never tried Branston's pickle, but I don't like store-bought ploughman's sandwiches very much, and DH hates it, so I probably won't be trying it any time soon.
Did someone mention peanut butter and marmite? I think I've just gone off my dinner!
I think any sort of nut butter+fruit based preserves works, really. Almonds, cashews, peanuts; apricot jam, apple butter, strawberry jam, grape jelly, etc. I can't understand why it seems so wierd to the Brits!