A combustion chamber assembly comprises a combustion chamber and a plurality of nozzle guide vanes. Each nozzle guide vane comprises an inner platform, an outer platform and an aerofoil. The combustion chamber comprises an annular wall which includes at least one box like structure. An outer wall of each box has a plurality of apertures for the supply of coolant into the box and the interior of the box is divided into at least two regions. The upstream end of each box has apertures to supply coolant from a first region of its interior onto an inner surface of the inner wall to form a film of coolant. The downstream end of each box has apertures to supply coolant from a second region of its interior onto a surface of the inner or outer platform of the nozzle guide vanes to form a film of coolant.