A stent delivery device comprising: a delivery cannula having at least one lumen extending therethrough and a proximal end; a nose cone dilator disposed at the proximal end of the delivery cannula, and an opening formed in a wall of the nose cone dilator, wherein the opening is in flow communication with the at least one cannula lumen; an expandable positioner disposed about the opening formed in the wall of the nose cone dilator, the expandable positioner comprising a wall defining an interior space, wherein the interior space of the expandable positioner is in flow communication with the at least one cannula lumen via the opening formed in the wall of the nose cone, wherein the positioner comprises a radially expanded condition and a radially contracted condition; wherein the device is configured such that flowing a fluid proximally through the at least one cannula lumen, through the opening formed in the wall of the nose cone dilator, and into the interior space of the positioner moves the positioner from the contracted condition to the expanded condition; and wherein the device further comprises a prosthesis carried on the delivery cannula, characterised in that the prosthesis comprises a stent graft comprising a proximal bare stent, the bare stent comprising at least one anchoring mechanism configured to engage a vessel wall and in that the distal end of the positioner is arranged proximally to the bare stent, the diameter of the expandable positioner in the expanded condition exceeding the diameter of the anchoring mechanism whereby the anchoring mechanism of the bare stent is prevented from engaging a vessel wall when the positioner is in an expanded configuration. a delivery cannula having at least one lumen extending therethrough and a proximal end; a nose cone dilator disposed at the proximal end of the delivery cannula, and an opening formed in a wall of the nose cone dilator, wherein the opening is in flow communication with the at least one cannula lumen; an expandable positioner disposed about the opening formed in the wall of the nose cone dilator, the expandable positioner comprising a wall defining an interior space, wherein the interior space of the expandable positioner is in flow communication with the at least one cannula lumen via the opening formed in the wall of the nose cone, wherein the positioner comprises a radially expanded condition and a radially contracted condition; wherein the device is configured such that flowing a fluid proximally through the at least one cannula lumen, through the opening formed in the wall of the nose cone dilator, and into the interior space of the positioner moves the positioner from the contracted condition to the expanded condition; and wherein the device further comprises a prosthesis carried on the delivery cannula, characterised in that the prosthesis comprises a stent graft comprising a proximal bare stent, the bare stent comprising at least one anchoring mechanism configured to engage a vessel wall and in that the distal end of the positioner is arranged proximally to the bare stent, the diameter of the expandable positioner in the expanded condition exceeding the diameter of the anchoring mechanism whereby the anchoring mechanism of the bare stent is prevented from engaging a vessel wall when the positioner is in an expanded configuration. wherein the device further comprises a prosthesis carried on the delivery cannula, characterised in that the prosthesis comprises a stent graft comprising a proximal bare stent, the bare stent comprising at least one anchoring mechanism configured to engage a vessel wall and in that the distal end of the positioner is arranged proximally to the bare stent, the diameter of the expandable positioner in the expanded condition exceeding the diameter of the anchoring mechanism whereby the anchoring mechanism of the bare stent is prevented from engaging a vessel wall when the positioner is in an expanded configuration.