Barbecued fillet of beef with horseradish butter recipe

Ingredients

• 1.2kg British beef fillet, cut from the fatter end of the fillet
• 1 tsp sea salt flakes
• 1 tsp coarsely ground black pepper
• 1 tsp dried thyme
• ½ tsp dried sage
• Olive oil for coating
• 50g lightly salted butter, at room temperature
• 1 small garlic clove, crushed
• 1 tbsp finely grated fresh horseradish
• 2 tsp finely chopped fresh chives
• Serve with chunky potato gratin
• Butter for greasing
• 1kg evenly sized floury potatoes such as King Edward
• 300ml whole milk
• 300ml double cream
• 1 tbsp picked fresh thyme leaves
• 100g mature cheddar, grated
• Also useful
• Digital probe thermometer