A cutting tool holder (110; 110') adapted for mounting thereon a cutting insert (130; 130') having a top face, a bottom face (31B; 131B) and an insert bore (35; 135') extending between said top face and said bottom face, and having an inner surface (133; 133'); said holder comprising: a seat (120; 120') defined by a base surface (122; 122') and at least one side wall (124a; 124a'; 124b') angled to said base surface, a seat bore (25; 25; 125') extending along a bore axis, and having an open end at said base surface; a securing arrangement comprising a securing member (150; 150') extending between a proximal end and a distal end, the securing member having a head portion (51; 51"; 151") at said proximal end and having its distal end received within said seat bore; and a displacement arrangement adapted to displace the securing member along the bore axis of said seat bore between a mounting position in which said head portion protrudes from within the seat bore through said base surface into said seat to a first extent, defining a first gap distance between said head portion and said at least one side wall allowing said cutting insert to be placed within the seat and/or being fully removed from the seat, and a securing position in which said head portion protrudes from within the seat bore through said base surface into said seat to a second extent, smaller than said first extent, defining a second gap distance between said head portion and said at least one side wall smaller than said first gap distance, so as to engage the inner surface of said insert bore, thereby securing said insert between the head portion and the at least one side wall, and wherein said insert seat is further formed with a support surface (128; 128') configured for engaging and providing support to the head portion of said securing member at least in said securing position; wherein the head portion comprises a first conical portion (153'; 153′′′) with an outwardly diverging tapering angle so that the first conical portion is configured for coming into contact with the inner surface of the cutting insert (130; 130'), characterised in that, the head portion (51; 51"; 151") further comprises a second conical portion (155") with an inwardly converging tapering angle, the second conical portion (155") being configured for allowing removal of the cutting insert without obstructing it, wherein the first conical portion (153'; 153′′′) is further configured for coming into contact with the support surface (128; 128') of the insert seat. a seat (120; 120') defined by a base surface (122; 122') and at least one side wall (124a; 124a'; 124b') angled to said base surface, a seat bore (25; 25; 125') extending along a bore axis, and having an open end at said base surface; a securing arrangement comprising a securing member (150; 150') extending between a proximal end and a distal end, the securing member having a head portion (51; 51"; 151") at said proximal end and having its distal end received within said seat bore; and a displacement arrangement adapted to displace the securing member along the bore axis of said seat bore between a mounting position in which said head portion protrudes from within the seat bore through said base surface into said seat to a first extent, defining a first gap distance between said head portion and said at least one side wall allowing said cutting insert to be placed within the seat and/or being fully removed from the seat, and a securing position in which said head portion protrudes from within the seat bore through said base surface into said seat to a second extent, smaller than said first extent, defining a second gap distance between said head portion and said at least one side wall smaller than said first gap distance, so as to engage the inner surface of said insert bore, thereby securing said insert between the head portion and the at least one side wall, and wherein said insert seat is further formed with a support surface (128; 128') configured for engaging and providing support to the head portion of said securing member at least in said securing position; wherein the head portion comprises a first conical portion (153'; 153′′′) with an outwardly diverging tapering angle so that the first conical portion is configured for coming into contact with the inner surface of the cutting insert (130; 130'), characterised in that, the head portion (51; 51"; 151") further comprises a second conical portion (155") with an inwardly converging tapering angle, the second conical portion (155") being configured for allowing removal of the cutting insert without obstructing it, wherein the first conical portion (153'; 153′′′) is further configured for coming into contact with the support surface (128; 128') of the insert seat.