Combine the beef, tomato paste, Worcestershire sauce, breadcrumbs, salt and pepper. Form into 4 flat patties. Char-grill or barbecue on medium–high heat for 4 minutes each side or until cooked through. Set aside and keep warm. Char-grill or barbecue the bacon for 3 minutes each side.
To assemble the sandwiches, spread the bread with butter, top 4 slices with a patty each. Top with chutney, lettuce and bacon. Top with more bread, bacon, tomato and lettuce, finishing with a slice of bread. Serves 4.