Abstract: A syphon-operated closet bowl flush tank of the kind comprising an inverted bell (10) containing a liftable plunger disc (12) to initiate syphon action has a flush control valve (14) comprising a tubular body part (16) mounted vertically in the top (18) of the bell and extending above the bell. The valve further has a stem (20) movable in and guided by the body part, is shaped to define a flow path (22) through the body part, and has lower (24) and upper (26) portions extending respectively below and above the top of the bell. The body part has a downwardly facing valve seat (25) inside the bell and the stem has an upwardly facing valve seat (31) co-operating with the downwardly facing seat to make a valve closure. An inverted bell float (38) is provided on the top of the stem. The body part includes a spring ring (30) carried in a flange (23) of the tubular body part so that the valve can be fitted to an existing bell by access from only the top of the bell.