A sealing element for positioning radially outwardly of aerofoil blades of a gas turbine engine is provided. A radially inner surface region of the sealing element includes a seal structure having one or more inwardly projecting walls formed by additive layer, powder fed, laser weld deposition. The walls form a plurality of curved profile shapes which are arranged in a repeating pattern across the radially inner surface region. None of the walls intersects with any other wall. The curved profile shapes have no radii of curvature less than 0.5 mm.