Method of forming a cooling air passage in a gas turbine stationary blade shroud

A method of forming a cooling fluid passage in a gas turbine stationary blade shroud of a gas turbine stationary blade comprising:

• forming a cooling fluid groove in a side end face of a shroud of a stationary gas turbine blade, the side end face extending between an outer face and an inner blade face of the shroud, and
• the shroud having an axial direction, such that the cooling fluid groove extends axially along the side end face of the shroud and has an open portion extending axially along the side end face of the shroud;
• and
• covering the open portion of the groove with a plug so as to form a cooling fluid passage that extends axially through the shroud,
• wherein said forming comprises electric discharge machining the side end face of the shroud to form said groove and said open portion.