A blade has a root portion and elongate portion extending from the root portion to a tip. The elongate portion has an aerofoil-shaped cross section having leading and trailing edges and suction and pressure sides. The tip may include a gutter defining squealer. The squealer has a wall extending from the trailing edge and along a substantial portion of the tip perimeter. A main trailing edge cooling channel extends within the elongate portion in a direction from root to tip adjacent the trailing edge and exiting into the gutter. A gallery channel is arranged just behind the gutter and extends from an open end intersecting the main trailing edge cooling channel to a closed end located just behind a trailing edge apogee. Cooling channels extend from the gallery channel and through the squealer wall. The gallery channel diameter is greater at the open end than the closed end.