An annular seal comprising: an annular outer casing comprising a plurality of radially extending mount holes configured to receive a corresponding structure of a plurality of seal segments; the plurality of seal segments, wherein: the plurality of seal segments is coupled to the annular outer casing to cumulatively form an annular sealing surface; the annular sealing surface is configured to face a rotating structure to inhibit fluid leakage between the rotating structure and the annular sealing surface; and each seal segment of the plurality of seal segments is configured for independent radial movement relative to other seal segments of the plurality of seal segments and comprises a trunnion configured to be received within a respective one of the plurality of radially extending mount holes; and a plurality of spring components configured to bias the plurality of seal segments relative to the radial movement; characterised in that: the plurality of spring components comprises two spring components per seal segment of the plurality of seal segments, the two spring components comprise a forward spring component (130A, 130C, 130E, 130G) and an aft spring component (130B, 130D, 130F, 130H), and the forward spring component (130A, 130C, 130E, 130G) and the aft spring component (130B, 130D, 130F, 130H) are coupled to a flange of the annular outer casing and to a radially outer surface of each seal segment of the plurality of seal segments. an annular outer casing comprising a plurality of radially extending mount holes configured to receive a corresponding structure of a plurality of seal segments; the plurality of seal segments, wherein: the plurality of seal segments is coupled to the annular outer casing to cumulatively form an annular sealing surface; the annular sealing surface is configured to face a rotating structure to inhibit fluid leakage between the rotating structure and the annular sealing surface; and each seal segment of the plurality of seal segments is configured for independent radial movement relative to other seal segments of the plurality of seal segments and comprises a trunnion configured to be received within a respective one of the plurality of radially extending mount holes; and the plurality of seal segments is coupled to the annular outer casing to cumulatively form an annular sealing surface; the annular sealing surface is configured to face a rotating structure to inhibit fluid leakage between the rotating structure and the annular sealing surface; and each seal segment of the plurality of seal segments is configured for independent radial movement relative to other seal segments of the plurality of seal segments and comprises a trunnion configured to be received within a respective one of the plurality of radially extending mount holes; and a plurality of spring components configured to bias the plurality of seal segments relative to the radial movement; characterised in that: the plurality of spring components comprises two spring components per seal segment of the plurality of seal segments, the two spring components comprise a forward spring component (130A, 130C, 130E, 130G) and an aft spring component (130B, 130D, 130F, 130H), and the forward spring component (130A, 130C, 130E, 130G) and the aft spring component (130B, 130D, 130F, 130H) are coupled to a flange of the annular outer casing and to a radially outer surface of each seal segment of the plurality of seal segments.