A flushing device (20) comprising an inner sleeve (21), axially slidable relative to an outer sleeve (23). The inner (21) and outer (23) sleeves cooperate to define an inner passage (32) for the flow of a fluid, and are permanently coupled such that there is substantially no rotational movement between the two sleeves. The inner passage (32) has an inlet (22b) and an outlet (22a). The outer sleeve (23) has a plurality of flushing outlets (33) which, when the flushing device (20) is in an open condition allow fluid to be diverted from the inner passage (32). The flushing device (20) also comprises an indexing mechanism (80) which indexes between a first position, wherein the plurality of flushing outlets (33) are blocked from the internal passage (32) such that the flushing device (20) is in a closed condition, to a second position, wherein the plurality of flushing outlets (33) register with the internal passage (32) such that the flushing device (20) is in the open condition. When fluid flows through the flushing device (20), the flushing device (20) is configured such that it remains in the selected open or closed condition regardless of the forces acting thereupon.