A wind or tidal turbine blade having an attachment, the attachment including: a support portion of the turbine blade, the support portion having opposite surfaces; an insert adapted to mount a bolt for attaching the support portion to another structure; and a mounting for fitting the insert to the support portion, the mounting including a layer extending over a front face of the insert and bonded to the opposite surfaces of the support portion on opposite sides of the insert, the layer permitting passage of a bolt therethrough to or from the insert.