Melt butter in 2 litre saucepan over low heat. Stir in flour, salt, pepper, mustard and Worcestershire sauce. Cook over low heat, stirring constantly, until smooth and bubbly. Remove from heat. Stir in milk. Heat to boiling, stirring constantly. Boil and stir 1 minute. Gradually stir wine into sauce mixture; stir in cheese. Heat over low heat, stirring constantly, until cheese is melted. Serve over toast. Sprinkle with paprika if desired.