Abstract: The disclosure of this invention pertains to a gas turbine engine having an annular combustion chamber having an outlet duct to turbine entry vanes, an extension of the combustion chamber connecting a radially outer wall of the duct to fixed structure at a position adjacent the downstream and of the vanes, wherein the wall is covergent in the downstream direction, the extension is connected to the wall at a location upstream of the downstream extremity thereof, and cooling air passages ae arranged to lead cooling air to the junction so that on heating of chamber in operation said extremity expands radially outwardly and in the downstream direction thereby to make sealing engagement with an adjacent extremity of a shroud ring of the vanes.