An airfoil, comprising: an airfoil section having an external wall and an internal wall, said internal wall defining a reference plane extending in a spanwise direction along a surface of said internal wall; a first cavity and a second cavity separated by said internal wall; a plurality of crossover passages within said internal wall and connecting said first cavity to said second cavity, each of said plurality of crossover passages defining a passage axis, said plurality of crossover passages distributed in said spanwise direction and arranged such that said passage axis of each of said plurality of crossover passages intersects a surface of said second cavity; and wherein said passage axis of at least one of said plurality of crossover passages is arranged at a first lateral angle relative to a localized region of reference plane, and said passage axis of another one of said plurality of crossover passages is arranged at a second, different lateral angle relative to said localized region of said reference plane; characterised in that: said passage axis of each of said plurality of crossover passages is arranged at a radial angle relative to said localized region of said reference plane such that said radial angle of at least some of said plurality of crossover passages differs in said spanwise direction; the airfoil comprises a plurality of film cooling passages within said external wall and extending from said surface of said second cavity; and at least some of said plurality of film cooling passages define a first axis common with said passage axis of one of said plurality of crossover passages. an airfoil section having an external wall and an internal wall, said internal wall defining a reference plane extending in a spanwise direction along a surface of said internal wall; a first cavity and a second cavity separated by said internal wall; a plurality of crossover passages within said internal wall and connecting said first cavity to said second cavity, each of said plurality of crossover passages defining a passage axis, said plurality of crossover passages distributed in said spanwise direction and arranged such that said passage axis of each of said plurality of crossover passages intersects a surface of said second cavity; and wherein said passage axis of at least one of said plurality of crossover passages is arranged at a first lateral angle relative to a localized region of reference plane, and said passage axis of another one of said plurality of crossover passages is arranged at a second, different lateral angle relative to said localized region of said reference plane; characterised in that: said passage axis of each of said plurality of crossover passages is arranged at a radial angle relative to said localized region of said reference plane such that said radial angle of at least some of said plurality of crossover passages differs in said spanwise direction; the airfoil comprises a plurality of film cooling passages within said external wall and extending from said surface of said second cavity; and at least some of said plurality of film cooling passages define a first axis common with said passage axis of one of said plurality of crossover passages. said passage axis of each of said plurality of crossover passages is arranged at a radial angle relative to said localized region of said reference plane such that said radial angle of at least some of said plurality of crossover passages differs in said spanwise direction; the airfoil comprises a plurality of film cooling passages within said external wall and extending from said surface of said second cavity; and at least some of said plurality of film cooling passages define a first axis common with said passage axis of one of said plurality of crossover passages.