A component for use in a hot gas path of gas turbine engine, the component comprising: a body including an outer surface that is exposed, in use, to a working fluid having a high temperature in the hot gas path; an internal cooling circuit (86, 160) in the body carrying a cooling medium (88, 190); a primary cooling pathway spaced internally from the outer surface in the body and in fluid communication with the internal cooling circuit (86, 160), the primary cooling pathway, in use, fluidly communicating a primary flow (192, 192') of the cooling medium (88, 190) therethrough from the internal cooling circuit (86, 160); and a secondary cooling pathway in the body and in fluid communication with the internal cooling circuit (86, 160), the secondary cooling pathway fluidly incommunicative and spaced internally from the primary cooling pathway, characterised in that in response to an overheating event in use, the secondary cooling pathway opens at a first opening to the primary cooling pathway to allow a secondary flow of cooling medium (88, 190) through to the primary cooling pathway from the secondary cooling pathway, wherein, in use, the primary flow (192, 192') of the cooling medium (88, 190) flows in the primary cooling pathway prior to the overheating event, and the secondary flow of cooling medium (88, 190) does not flow in the secondary cooling pathway until after the overheating event; wherein the overheating event includes a temperature in the primary cooling pathway causing, in use, a portion of the body to reach or exceed a predetermined temperature, causing the portion of the body to change state in such a way as to allow its removal to define the first opening, thereby allowing the secondary flow of cooling medium (88, 190) through to the primary cooling pathway. a body including an outer surface that is exposed, in use, to a working fluid having a high temperature in the hot gas path; an internal cooling circuit (86, 160) in the body carrying a cooling medium (88, 190); a primary cooling pathway spaced internally from the outer surface in the body and in fluid communication with the internal cooling circuit (86, 160), the primary cooling pathway, in use, fluidly communicating a primary flow (192, 192') of the cooling medium (88, 190) therethrough from the internal cooling circuit (86, 160); and a secondary cooling pathway in the body and in fluid communication with the internal cooling circuit (86, 160), the secondary cooling pathway fluidly incommunicative and spaced internally from the primary cooling pathway, characterised in that in response to an overheating event in use, the secondary cooling pathway opens at a first opening to the primary cooling pathway to allow a secondary flow of cooling medium (88, 190) through to the primary cooling pathway from the secondary cooling pathway, wherein, in use, the primary flow (192, 192') of the cooling medium (88, 190) flows in the primary cooling pathway prior to the overheating event, and the secondary flow of cooling medium (88, 190) does not flow in the secondary cooling pathway until after the overheating event; wherein the overheating event includes a temperature in the primary cooling pathway causing, in use, a portion of the body to reach or exceed a predetermined temperature, causing the portion of the body to change state in such a way as to allow its removal to define the first opening, thereby allowing the secondary flow of cooling medium (88, 190) through to the primary cooling pathway.