A head part of an annular gas turbine combustion chamber including: an end wall with a passage opening for accommodating a burner, the end wall including a set back portion adjacent the passage opening; a heat shield covering a back side of the end wall which faces towards the combustion chamber, the heat shield including a protruding portion shaped to cooperate with the set back portion of the end wall; and a burner collar adapted to fit within the passage opening and receive a burner, the burner collar including a protruding portion radially protruding from an outer surface of the burner collar; wherein the head part of the annular gas turbine combustion chamber is configured such that in an installed configuration the protruding portion of the burner collar is held between the protruding portion of the heat shield and the set back portion of the end wall.