Cooling air is provided from a source of cooling air through a cooling air circuit in a turbine section of a gas turbine engine. A first portion of cooling air is provided from the source along a first path of the circuit to a plurality of blades associated with a stage of the turbine section. A second portion of cooling air is provided from the source along a second path of the circuit. The second path includes a turbine disc bore where the cooling air provides cooling to a radially innermost portion of at least one turbine disc that forms a part of a rotor of the engine. The second path is independent from the first path such that the second portion of cooling air bypasses the stage and is not mixed with the first portion of cooling air in the circuit after leaving the source.