The annulus is bound by an inner hub wall and an outer casing and includes a support structure, the support structure bearing the inner hub wall; at least one spigot passing through the hub wall and at least one strut arranged to pass through the spigot of the inner hub wall and across the annulus. The strut has a first end having an abutment arm extending to form an abutment shoulder. Alignable holes pass through the abutment arm and the spigot and these holes are configured to receive a cross pin which is in turn configured to fit snugly through the holes. The configuration is such that, the abutment rim and abutment shoulder are located radially inwardly of the holes and cross pin and outside of the annulus.