Peel n' Eat Boiled Shrimp with Cocktail Sauce

Ingredients

• 2½ tablespoons Old Bay seasoning
• 3 tablespoons unsalted butter
• 1 cup beer
• 1 cup water
• 2 lb extra large shrimp ((26/30), shell split and deveined, thawed if frozen)
• 6 tablespoons ketchup
• ½ tablespoon prepared horseradish ((see note))
• 1 tablespoon freshly squeezed lemon juice, (from 1 lemon)
• Pinch cayenne pepper