The present invention relates to an actuatable seal (14) for an aerofoil blade tip, for providing a seal between the blade tip (12) and an adjacent surface (10) over which the blade tip passes in use. The seal comprises a flexible member that is arranged in use to be mounted on the tip of a rotating aerofoil blade and to flex towards the surface under the action of centrifugal force when the blade rotates. The seal further comprises an actuator means provided on the flexible member and operably arranged in use to deflect at least a portion of the flexible member away from the surface.