A gas turbine engine combustor, comprising: an inner liner and having an inner surface, an outer surface, an upstream end, a downstream end, the inner liner extending in an axial direction between the upstream and downstream ends (214,216); an outer liner having an inner surface, an outer surface, an upstream end, and a downstream end, the outer liner extending in the axial direction between the upstream and downstream ends (224, 226) and spaced apart from, and at least partially surrounding, the inner liner; a dome assembly coupled between the upstream ends of the inner and outer annular liners (202, 204) to define a combustion chamber between the inner liner outer surface and the outer liner inner surface; and two or more sets of effusion cooling holes extending through the outer liner between the outer liner outer and inner surfaces (222, 218), each set of effusion cooling holes including one or more initial rows of effusion cooling holes, one or more final rows of effusion cooling holes disposed downstream of the one or more initial rows, and a plurality of interposed rows of effusion cooling holes disposed between the initial and final rows (406, 408); characterised in that: each effusion cooling hole in the one or more initial rows is disposed at a tangential angle of between about 70 deg. and about 90 deg. relative to the axial direction, each effusion cooling hole in the one or more final rows is disposed at a tangential angle of between about 0 deg. and about 20 deg. relative to the axial direction, and each effusion cooling hole in each of the interposed rows disposed at a tangential angle, relative to the axial direction, that is less than the tangential angle of the effusion cooling holes in the one or more initial rows and greater than the tangential angle of the effusion cooling holes in the one or more final rows, an inner liner and having an inner surface, an outer surface, an upstream end, a downstream end, the inner liner extending in an axial direction between the upstream and downstream ends (214,216); an outer liner having an inner surface, an outer surface, an upstream end, and a downstream end, the outer liner extending in the axial direction between the upstream and downstream ends (224, 226) and spaced apart from, and at least partially surrounding, the inner liner; a dome assembly coupled between the upstream ends of the inner and outer annular liners (202, 204) to define a combustion chamber between the inner liner outer surface and the outer liner inner surface; and two or more sets of effusion cooling holes extending through the outer liner between the outer liner outer and inner surfaces (222, 218), each set of effusion cooling holes including one or more initial rows of effusion cooling holes, one or more final rows of effusion cooling holes disposed downstream of the one or more initial rows, and a plurality of interposed rows of effusion cooling holes disposed between the initial and final rows (406, 408); characterised in that: each effusion cooling hole in the one or more initial rows is disposed at a tangential angle of between about 70 deg. and about 90 deg. relative to the axial direction, each effusion cooling hole in the one or more final rows is disposed at a tangential angle of between about 0 deg. and about 20 deg. relative to the axial direction, and each effusion cooling hole in each of the interposed rows disposed at a tangential angle, relative to the axial direction, that is less than the tangential angle of the effusion cooling holes in the one or more initial rows and greater than the tangential angle of the effusion cooling holes in the one or more final rows, each effusion cooling hole in the one or more initial rows is disposed at a tangential angle of between about 70 deg. and about 90 deg. relative to the axial direction, each effusion cooling hole in the one or more final rows is disposed at a tangential angle of between about 0 deg. and about 20 deg. relative to the axial direction, and each effusion cooling hole in each of the interposed rows disposed at a tangential angle, relative to the axial direction, that is less than the tangential angle of the effusion cooling holes in the one or more initial rows and greater than the tangential angle of the effusion cooling holes in the one or more final rows,