A nacelle (250; 350; 450) configured to encircle an engine about an axis of rotation in use, the nacelle (250; 350; 450) comprising: an inlet cowling (202; 302; 402) defining an inlet of the nacelle (250; 350; 450), wherein the inlet cowling (202; 302; 402) comprises: an inlet cowling outer external surface (204, 304, 404) defining an outermost circumferential surface of the inlet cowling (202; 302; 402); an inlet cowling maximum point (207, 307, 407) which is the most radially outward point on the inlet cowling external surface (204, 304, 404) and an inlet cowling aft edge (210; 310; 410), wherein the inlet cowling aft edge (210; 310; 410) comprises an aft edge length (214, 314, 414) which is a length extending in a direction radially from the axis of rotation; a boat tail cowling (230; 330; 430) disposed aft of the inlet cowling (202; 302; 402), wherein the boat tail cowling (230; 330; 430) comprises a boat tail cowling outer external surface (232, 332, 432) defining an outermost circumferential surface of the boat tail cowling (230; 330; 430), and a boat tail cowling forward edge (224; 324; 424) which is the forward-most edge of the boat tail cowling (230; 330; 430), wherein the boat tail cowling forward edge (224; 324; 424) extends in a direction radially from the boat tail cowling external surface (232, 332, 432), wherein the boat tail cowling forward edge (224; 324; 424) has a forward edge length (226, 326, 426), and wherein the boat tail cowling forward edge (224; 324; 424) is disposed adjacent to the inlet cowling aft edge (210; 310; 410), characterised in that the boat tail cowling forward edge length (226, 326, 426) is shorter than the inlet cowling aft edge length (214, 314, 414), forming a step (212, 312, 412), the step (212, 312, 412) being defined by a portion of the inlet cowling aft edge (210; 310; 410) that is radially outward of the boat tail cowling forward edge (224; 324; 424); and in that the nacelle further comprises a transition fairing (220; 320; 420) coupled to the boat tail cowling external surface (232; 332; 432) of the boat tail cowling (230; 330; 430), wherein the transition fairing (220; 320; 420) comprises: an inner surface coupled and/or disposed adjacent to the boat tail cowling external surface (232; 332; 432), a fairing forward surface (221, 321, 421) disposed adjacent to the inlet cowling aft edge (210; 310; 410) and a fairing ramp surface (222; 322; 422) providing a transition surface between the inlet cowling aft edge (210; 310; 410) and the boat tail cowling external surface (232; 332; 432). an inlet cowling (202; 302; 402) defining an inlet of the nacelle (250; 350; 450), wherein the inlet cowling (202; 302; 402) comprises: an inlet cowling outer external surface (204, 304, 404) defining an outermost circumferential surface of the inlet cowling (202; 302; 402); an inlet cowling maximum point (207, 307, 407) which is the most radially outward point on the inlet cowling external surface (204, 304, 404) and an inlet cowling aft edge (210; 310; 410), wherein the inlet cowling aft edge (210; 310; 410) comprises an aft edge length (214, 314, 414) which is a length extending in a direction radially from the axis of rotation; a boat tail cowling (230; 330; 430) disposed aft of the inlet cowling (202; 302; 402), wherein the boat tail cowling (230; 330; 430) comprises a boat tail cowling outer external surface (232, 332, 432) defining an outermost circumferential surface of the boat tail cowling (230; 330; 430), and a boat tail cowling forward edge (224; 324; 424) which is the forward-most edge of the boat tail cowling (230; 330; 430), wherein the boat tail cowling forward edge (224; 324; 424) extends in a direction radially from the boat tail cowling external surface (232, 332, 432), wherein the boat tail cowling forward edge (224; 324; 424) has a forward edge length (226, 326, 426), and wherein the boat tail cowling forward edge (224; 324; 424) is disposed adjacent to the inlet cowling aft edge (210; 310; 410), characterised in that the boat tail cowling forward edge length (226, 326, 426) is shorter than the inlet cowling aft edge length (214, 314, 414), forming a step (212, 312, 412), the step (212, 312, 412) being defined by a portion of the inlet cowling aft edge (210; 310; 410) that is radially outward of the boat tail cowling forward edge (224; 324; 424); and in that the nacelle further comprises a transition fairing (220; 320; 420) coupled to the boat tail cowling external surface (232; 332; 432) of the boat tail cowling (230; 330; 430), wherein the transition fairing (220; 320; 420) comprises: an inner surface coupled and/or disposed adjacent to the boat tail cowling external surface (232; 332; 432), a fairing forward surface (221, 321, 421) disposed adjacent to the inlet cowling aft edge (210; 310; 410) and a fairing ramp surface (222; 322; 422) providing a transition surface between the inlet cowling aft edge (210; 310; 410) and the boat tail cowling external surface (232; 332; 432).