A flexible pipe body comprising: an elongate curvature sensor ; and a tensile armour layer comprising helically wound tensile armour wires , the curvature sensor being positioned within the tensile armour layer helically wound adjacent to at least one tensile armour wire such that bending strain applied to the flexible pipe body is transmitted to the curvature sensor ; wherein the curvature sensor is smaller than an adjacent tensile armour wire in at least one of depth and width and arranged to slide longitudinally relative to the adjacent tensile armour wire ; wherein the curvature sensor comprises: an elongate, flexible sensor body ; a first elongate strain sensor disposed along the sensor body within a neutral plane of the sensor body such that bending of the sensor body in a plane extending along the length of the body and normal to the neutral plane does not apply strain to the first strain sensor ; a second elongate strain sensor disposed along the sensor body offset from the neutral plane ; and an optical fibre temperature sensor disposed along the sensor body loosely within a metal tube such that tensile strain and bending strain applied to the body is not transmitted to the optical fibre ; and wherein strain sensed by the first strain sensor is indicative of tensile strain applied along the length of the sensor body and strain sensed by the second strain sensor is indicative of the combination of tensile strain applied along the length of the sensor body and strain induced by bending the sensor body in the plane extending along the length of the sensor body and normal to the neutral plane . an elongate curvature sensor ; and a tensile armour layer comprising helically wound tensile armour wires , the curvature sensor being positioned within the tensile armour layer helically wound adjacent to at least one tensile armour wire such that bending strain applied to the flexible pipe body is transmitted to the curvature sensor ; wherein the curvature sensor is smaller than an adjacent tensile armour wire in at least one of depth and width and arranged to slide longitudinally relative to the adjacent tensile armour wire ; wherein the curvature sensor comprises: an elongate, flexible sensor body ; a first elongate strain sensor disposed along the sensor body within a neutral plane of the sensor body such that bending of the sensor body in a plane extending along the length of the body and normal to the neutral plane does not apply strain to the first strain sensor ; a second elongate strain sensor disposed along the sensor body offset from the neutral plane ; and an optical fibre temperature sensor disposed along the sensor body loosely within a metal tube such that tensile strain and bending strain applied to the body is not transmitted to the optical fibre ; and an elongate, flexible sensor body ; a first elongate strain sensor disposed along the sensor body within a neutral plane of the sensor body such that bending of the sensor body in a plane extending along the length of the body and normal to the neutral plane does not apply strain to the first strain sensor ; a second elongate strain sensor disposed along the sensor body offset from the neutral plane ; and an optical fibre temperature sensor disposed along the sensor body loosely within a metal tube such that tensile strain and bending strain applied to the body is not transmitted to the optical fibre ; and wherein strain sensed by the first strain sensor is indicative of tensile strain applied along the length of the sensor body and strain sensed by the second strain sensor is indicative of the combination of tensile strain applied along the length of the sensor body and strain induced by bending the sensor body in the plane extending along the length of the sensor body and normal to the neutral plane . <EOS>