A cutting tool holder blade having opposite ends and a longitudinal mid-axis (A) lying on a mid-plane (P) and extending between the opposite ends , the cutting tool holder blade comprising: at least one insert clamping portion with a front plane (F) perpendicular to the mid-plane (P), the insert clamping portion having at least one insert pocket , the insert pocket comprising: a base jaw having a base jaw abutment surface ; a clamping jaw resiliently connected to the base jaw in a unitary one-piece construction, the clamping jaw having a clamping surface facing opposite the base jaw abutment surface and an insert stop surface ; and a curved inner surface extending from the base jaw abutment surface towards and along the clamping jaw , the curved inner surface having a front extremity portion , wherein a first minimum longitudinal distance (D1) between the front extremity portion and the front plane (F) is smaller than a second minimum longitudinal distance (D2) between the clamping surface and the front plane (F), characterised in that the holder blade is formed of hard metal, the cutting tool holder blade is mirror-symmetric about the mid-plane (P) with the at least one insert clamping portion having two insert pockets located on opposite sides of the mid-plane (P), the curved inner surface has an inner extremity portion , spaced apart from the front extremity portion , with a minimum transverse distance (H) extending between the inner extremity portions of both insert pockets in the same insert clamping portion , a third longitudinal distance (D3) extends between the inner extremity portion of each insert pocket and the front plane (F), and the minimum transverse distance (H) is greater than the third longitudinal distance (D3). at least one insert clamping portion with a front plane (F) perpendicular to the mid-plane (P), the insert clamping portion having at least one insert pocket , the insert pocket comprising: a base jaw having a base jaw abutment surface ; a clamping jaw resiliently connected to the base jaw in a unitary one-piece construction, the clamping jaw having a clamping surface facing opposite the base jaw abutment surface and an insert stop surface ; and a curved inner surface extending from the base jaw abutment surface towards and along the clamping jaw , the curved inner surface having a front extremity portion , a base jaw having a base jaw abutment surface ; a clamping jaw resiliently connected to the base jaw in a unitary one-piece construction, the clamping jaw having a clamping surface facing opposite the base jaw abutment surface and an insert stop surface ; and a curved inner surface extending from the base jaw abutment surface towards and along the clamping jaw , the curved inner surface having a front extremity portion , wherein a first minimum longitudinal distance (D1) between the front extremity portion and the front plane (F) is smaller than a second minimum longitudinal distance (D2) between the clamping surface and the front plane (F), characterised in that the holder blade is formed of hard metal, the cutting tool holder blade is mirror-symmetric about the mid-plane (P) with the at least one insert clamping portion having two insert pockets located on opposite sides of the mid-plane (P), the curved inner surface has an inner extremity portion , spaced apart from the front extremity portion , with a minimum transverse distance (H) extending between the inner extremity portions of both insert pockets in the same insert clamping portion , a third longitudinal distance (D3) extends between the inner extremity portion of each insert pocket and the front plane (F), and the minimum transverse distance (H) is greater than the third longitudinal distance (D3). <EOS>