A fuel injector (94, 200, 250, 300) for use in a combustor apparatus of a gas turbine engine, the fuel injector extending, in use, through an opening (100, 222, 280, 332) formed in a liner (36, 224, 282, 334) and into an inner volume of the liner, the fuel injector comprising: an outer wall (102, 202, 252, 302) defining an interior volume therein and including at least one opening formed therein, at least a portion of said outer wall located in the inner volume of the liner, wherein a distal end of the outer wall comprises a radially inner section having an inner bore; an intermediate wall (120, 204, 254, 304) disposed in said outer wall interior volume and spaced from said outer wall such that a first gap (124, 218, 276, 328) is formed between said outer wall and said intermediate wall, said intermediate wall defining an internal volume and including at least one aperture (130, 216, 274, 326) formed therein; an inner wall (110, 206, 256, 306) disposed in said intermediate wall internal volume and spaced from said intermediate wall such that a second gap (134, 214, 273, 324) is formed between said intermediate wall and said inner wall, said second gap receiving cooling fluid that cools the fuel injector, said inner wall defining a passageway therein that receives fuel and delivers said fuel to the inner volume of the liner downstream from a main combustion zone defined by the liner; and wherein said cooling fluid in said second gap: provides convective cooling to said intermediate wall as it flows within said second gap; and flows through said at least one aperture in said intermediate wall into said first gap where said cooling fluid provides impingement cooling to said outer wall and provides convective cooling to said outer wall as it flows within said first gap, characterised in that said inner wall is received in said inner bore, in that said at least one opening in said outer wall opens into said inner volume of the liner and is adjacent said inner bore, and in that said cooling fluid flows through said at least one opening in said outer wall into said inner volume of the liner. an outer wall (102, 202, 252, 302) defining an interior volume therein and including at least one opening formed therein, at least a portion of said outer wall located in the inner volume of the liner, wherein a distal end of the outer wall comprises a radially inner section having an inner bore; an intermediate wall (120, 204, 254, 304) disposed in said outer wall interior volume and spaced from said outer wall such that a first gap (124, 218, 276, 328) is formed between said outer wall and said intermediate wall, said intermediate wall defining an internal volume and including at least one aperture (130, 216, 274, 326) formed therein; an inner wall (110, 206, 256, 306) disposed in said intermediate wall internal volume and spaced from said intermediate wall such that a second gap (134, 214, 273, 324) is formed between said intermediate wall and said inner wall, said second gap receiving cooling fluid that cools the fuel injector, said inner wall defining a passageway therein that receives fuel and delivers said fuel to the inner volume of the liner downstream from a main combustion zone defined by the liner; and wherein said cooling fluid in said second gap: provides convective cooling to said intermediate wall as it flows within said second gap; and flows through said at least one aperture in said intermediate wall into said first gap where said cooling fluid provides impingement cooling to said outer wall and provides convective cooling to said outer wall as it flows within said first gap, characterised in that said inner wall is received in said inner bore, in that said at least one opening in said outer wall opens into said inner volume of the liner and is adjacent said inner bore, and in that said cooling fluid flows through said at least one opening in said outer wall into said inner volume of the liner. provides convective cooling to said intermediate wall as it flows within said second gap; and flows through said at least one aperture in said intermediate wall into said first gap where said cooling fluid provides impingement cooling to said outer wall and provides convective cooling to said outer wall as it flows within said first gap,