A cooled turbine blade comprising: a root for fixing the cooled turbine blade to a turbine rotor; an airfoil extending along a radial axis from the root, the airfoil defining a single aft airfoil cooling passage that extends radially through the airfoil proximate a trailing edge portion of the airfoil wherein the single aft airfoil passage is located within a distance of a trailing edge that is less than 25 per cent of the airfoil chord length; and a tip shroud disposed at a radially outward end of the airfoil, extending in a circumferential direction from the airfoil, and defining, within the tip shroud, a core plenum and a peripheral plenum; the airfoil defining an aft cooling inlet for providing a single aft stream of cooling fluid to the single aft airfoil cooling passage and defining a single aft cooling exit for discharging the single aft stream of cooling fluid from the aft airfoil cooling passage to the peripheral plenum, wherein an entire amount of the single aft stream directly routed to the peripheral plenum is routed through the single aft airfoil cooling passage; the tip shroud defining at least one peripheral plenum vent for discharging the single aft stream of cooling fluid from the peripheral plenum; and one or more core airfoil cooling passages defined by the airfoil, each of the one or more core airfoil cooling passages extending radially through a core section of the airfoil, the airfoil defining a core cooling inlet for providing a core stream of cooling fluid to the one or more core airfoil cooling passages and defining at least one core cooling exit for discharging the core stream of cooling fluid from the one or more core airfoil cooling passages to the core plenum; wherein the single aft cooling passage and the one or more core airfoil cooling passages are positioned to route the aft stream of cooling fluid and the core stream of cooling fluid to distinct plenums and wherein the one or more core airfoil cooling passages are located within a distance of a centre of the airfoil that is less than 25 percent of the airfoil chord length. a root for fixing the cooled turbine blade to a turbine rotor; an airfoil extending along a radial axis from the root, the airfoil defining a single aft airfoil cooling passage that extends radially through the airfoil proximate a trailing edge portion of the airfoil wherein the single aft airfoil passage is located within a distance of a trailing edge that is less than 25 per cent of the airfoil chord length; and a tip shroud disposed at a radially outward end of the airfoil, extending in a circumferential direction from the airfoil, and defining, within the tip shroud, a core plenum and a peripheral plenum; the airfoil defining an aft cooling inlet for providing a single aft stream of cooling fluid to the single aft airfoil cooling passage and defining a single aft cooling exit for discharging the single aft stream of cooling fluid from the aft airfoil cooling passage to the peripheral plenum, wherein an entire amount of the single aft stream directly routed to the peripheral plenum is routed through the single aft airfoil cooling passage; the tip shroud defining at least one peripheral plenum vent for discharging the single aft stream of cooling fluid from the peripheral plenum; and one or more core airfoil cooling passages defined by the airfoil, each of the one or more core airfoil cooling passages extending radially through a core section of the airfoil, the airfoil defining a core cooling inlet for providing a core stream of cooling fluid to the one or more core airfoil cooling passages and defining at least one core cooling exit for discharging the core stream of cooling fluid from the one or more core airfoil cooling passages to the core plenum; wherein the single aft cooling passage and the one or more core airfoil cooling passages are positioned to route the aft stream of cooling fluid and the core stream of cooling fluid to distinct plenums and wherein the one or more core airfoil cooling passages are located within a distance of a centre of the airfoil that is less than 25 percent of the airfoil chord length.