A gas turbine engine comprising: a combustor shell comprising a diffuser-facing side and a combustor-facing side ; and a combustor panel comprising an attachment feature having a central longitudinal axis and extending from a cold side of the combustor panel , the attachment feature comprising a tip portion and a base portion , wherein the attachment feature is configured to extend through the combustor shell such that the tip portion is disposed outward of a diffuser-facing side of the combustor shell , wherein the base portion is configured to be disposed between the cold side of the combustor panel and the diffuser-facing side of the combustor shell ; wherein the combustor panel is coupled to the combustor shell via the attachment feature , the attachment feature extending through a hole in the combustor shell , wherein an annular cooling cavity is defined between the combustor shell and the combustor panel ; and wherein the attachment feature defines a core passage extending from an inlet opening for receiving cooling air from a diffuser chamber that is at least partially defined by the diffuser-facing side of the combustor shell , the inlet opening defined on the tip portion and extending partially through the attachment feature to terminate within the attachment feature , and an offshoot passage extending from the core passage to an outlet opening for delivering the cooling air to the annular cooling cavity adjacent the attachment feature , the outlet opening defined on the base portion , the core passage and the offshoot passage collectively forming a cooling airflow conduit which extends through the attachment feature ; characterised in that : the outlet opening of the offshoot passage is at least partially disposed within the hole in the combustor shell . a combustor shell comprising a diffuser-facing side and a combustor-facing side ; and a combustor panel comprising an attachment feature having a central longitudinal axis and extending from a cold side of the combustor panel , the attachment feature comprising a tip portion and a base portion , wherein the attachment feature is configured to extend through the combustor shell such that the tip portion is disposed outward of a diffuser-facing side of the combustor shell , wherein the base portion is configured to be disposed between the cold side of the combustor panel and the diffuser-facing side of the combustor shell ; wherein the combustor panel is coupled to the combustor shell via the attachment feature , the attachment feature extending through a hole in the combustor shell , wherein an annular cooling cavity is defined between the combustor shell and the combustor panel ; and wherein the attachment feature defines a core passage extending from an inlet opening for receiving cooling air from a diffuser chamber that is at least partially defined by the diffuser-facing side of the combustor shell , the inlet opening defined on the tip portion and extending partially through the attachment feature to terminate within the attachment feature , and an offshoot passage extending from the core passage to an outlet opening for delivering the cooling air to the annular cooling cavity adjacent the attachment feature , the outlet opening defined on the base portion , the core passage and the offshoot passage collectively forming a cooling airflow conduit which extends through the attachment feature ; characterised in that : the outlet opening of the offshoot passage is at least partially disposed within the hole in the combustor shell . <EOS>