A stator assembly comprising: a compressor case including an arcuate wall having an aperture with circumferentially spaced first lateral surfaces; a stator vane having an outer platform with a notch; and an anti-rotation lug having a base received in the notch and a boss extending radially outward from the base, the base having a perimeter, and the boss being arranged within the perimeter and received in the aperture, the boss having second lateral surfaces engaging the first lateral surfaces in an interference fit relationship; characterised in that: the boss of the anti-rotation lug has a racetrack shape and the second lateral surfaces of the boss are spaced apart and are joined on opposing sides by second arcuate surfaces to provide the racetrack shape, the first lateral surfaces are parallel to one another and provide a circumferential aperture width, the second lateral surfaces are parallel with one another and provide a circumferential boss width, the boss width is greater than the aperture width, the first and second lateral surfaces (102, 108) are flat, the first lateral surfaces are joined by first arcuate surfaces opposite one another forming a racetrack-shaped aperture and providing an axial aperture length, the second arcuate surfaces provide an axial boss length, the aperture length greater than the boss length providing a clearance between the first arcuate surfaces and the second arcuate surfaces, the aperture is an axially extending elongated aperture, the notch is provided by spaced apart lateral walls extending in the axial direction, and the base provides lateral sides that engage the lateral walls of the notch. a compressor case including an arcuate wall having an aperture with circumferentially spaced first lateral surfaces; a stator vane having an outer platform with a notch; and an anti-rotation lug having a base received in the notch and a boss extending radially outward from the base, the base having a perimeter, and the boss being arranged within the perimeter and received in the aperture, the boss having second lateral surfaces engaging the first lateral surfaces in an interference fit relationship; characterised in that: the boss of the anti-rotation lug has a racetrack shape and the second lateral surfaces of the boss are spaced apart and are joined on opposing sides by second arcuate surfaces to provide the racetrack shape, the first lateral surfaces are parallel to one another and provide a circumferential aperture width, the second lateral surfaces are parallel with one another and provide a circumferential boss width, the boss width is greater than the aperture width, the first and second lateral surfaces (102, 108) are flat, the first lateral surfaces are joined by first arcuate surfaces opposite one another forming a racetrack-shaped aperture and providing an axial aperture length, the second arcuate surfaces provide an axial boss length, the aperture length greater than the boss length providing a clearance between the first arcuate surfaces and the second arcuate surfaces, the aperture is an axially extending elongated aperture, the notch is provided by spaced apart lateral walls extending in the axial direction, and the base provides lateral sides that engage the lateral walls of the notch.