A leaf seal for effecting a seal between coaxials and relatively rotating components. The seal has annular pack of stacked leaves, the pack mountable to first one of components at leaves root portions and extending towards other component end edges of leaves presented for air-riding interaction with other component during relative rotation between components. In use, pressure drop is maintained axially across the pack, which includes first set of leaves arranged around the pack, each to present an end edge at least part in relationship with other component. The pack includes second set of leaves circumferentially interspersed throughout the first set. The first and second sets, leaves help define, around the pack, circumferential spaces between end edges of first set's successive leaves, the spaces create circumferential variation in pressure around the pack contributing to the generation of hydrodynamic lift between pack and other component during relative rotation between components.