A thrust reverser inner fixed structure, comprising: an inner skin; an outer skin; a cellular core disposed between the inner skin and the outer skin; and a reinforcement lattice comprising a plurality of reinforcement members (817, 819) extending in a thickness direction through the cellular core between the inner skin and the outer skin, wherein: each of the reinforcement members also extends in lateral direction of the cellular core, lateral directions associated with a first set of reinforcement members intersecting lateral directions associated with a second set of reinforcement members to thereby form the reinforcement lattice; wherein each reinforcement member comprises: a central segment extending radially through the cellular core, the central segment having a first end and a second end; and a first end segment extending from the first end of the central segment substantially parallel to the inner skin and bonded thereto; characterised in that the outer skin is perforated; the inner skin is imperforate; the cellular core is bonded to both the inner and outer skins; and the central segment is bonded along at least a portion of its length to the cellular core; and wherein the second end of each central segment is proximate to the outer skin and the outer skin is not bonded to any of the reinforcement members. an inner skin; an outer skin; a cellular core disposed between the inner skin and the outer skin; and a reinforcement lattice comprising a plurality of reinforcement members (817, 819) extending in a thickness direction through the cellular core between the inner skin and the outer skin, wherein: each of the reinforcement members also extends in lateral direction of the cellular core, lateral directions associated with a first set of reinforcement members intersecting lateral directions associated with a second set of reinforcement members to thereby form the reinforcement lattice; wherein each reinforcement member comprises: a central segment extending radially through the cellular core, the central segment having a first end and a second end; and a first end segment extending from the first end of the central segment substantially parallel to the inner skin and bonded thereto; characterised in that the outer skin is perforated; the inner skin is imperforate; the cellular core is bonded to both the inner and outer skins; and the central segment is bonded along at least a portion of its length to the cellular core; and wherein the second end of each central segment is proximate to the outer skin and the outer skin is not bonded to any of the reinforcement members. each of the reinforcement members also extends in lateral direction of the cellular core, lateral directions associated with a first set of reinforcement members intersecting lateral directions associated with a second set of reinforcement members to thereby form the reinforcement lattice; wherein each reinforcement member comprises: a central segment extending radially through the cellular core, the central segment having a first end and a second end; and a first end segment extending from the first end of the central segment substantially parallel to the inner skin and bonded thereto; characterised in that the outer skin is perforated; the inner skin is imperforate; the cellular core is bonded to both the inner and outer skins; and the central segment is bonded along at least a portion of its length to the cellular core; and wherein the second end of each central segment is proximate to the outer skin and the outer skin is not bonded to any of the reinforcement members. a central segment extending radially through the cellular core, the central segment having a first end and a second end; and a first end segment extending from the first end of the central segment substantially parallel to the inner skin and bonded thereto; characterised in that the outer skin is perforated; the inner skin is imperforate; the cellular core is bonded to both the inner and outer skins; and the central segment is bonded along at least a portion of its length to the cellular core; and characterised in that the outer skin is perforated; the inner skin is imperforate; the cellular core is bonded to both the inner and outer skins; and the central segment is bonded along at least a portion of its length to the cellular core; and wherein the second end of each central segment is proximate to the outer skin and the outer skin is not bonded to any of the reinforcement members.