A sampling port having: a body having a space having a longitudinal direction, open at a first end and adapted to receive a sampling vial; the body comprising first and second portions spaced along the longitudinal direction with the first portion nearer the first end than the second portion; the first portion adapted to receive a tubular body having a maximum first diameter; the second portion adapted to receive a tubular body having a maximum second diameter, smaller than the first diameter; a cannula having an axis and extending longitudinally along the space with a pointed end facing the open first end, whereby a sampling vial passed into the space from the open first end may be impaled on the cannula; at least one guide member mounted on or connected to the body for movement about at least one hinge located at or adjacent the first end characterized in that the at least one guide member is configured for movement between a guide position and a non-guide position, wherein: in the guide position at least part of a free end of at least one guide member extends into the second portion to reduce the effective size of part of the second portion to receive a tubular body of a maximum fourth diameter, and in the non-guide position all of the at least one guide member is located outside of the space, and the at least one guide member and the body are configured so that the path of the free end of the or each of the at least one guide member as the or each of the at least one guide member moves about the respective at least one hinge between the guide and non-guide positions clears the body and extends through the first end. a body having a space having a longitudinal direction, open at a first end and adapted to receive a sampling vial; the body comprising first and second portions spaced along the longitudinal direction with the first portion nearer the first end than the second portion; the first portion adapted to receive a tubular body having a maximum first diameter; the second portion adapted to receive a tubular body having a maximum second diameter, smaller than the first diameter; the first portion adapted to receive a tubular body having a maximum first diameter; the second portion adapted to receive a tubular body having a maximum second diameter, smaller than the first diameter; a cannula having an axis and extending longitudinally along the space with a pointed end facing the open first end, whereby a sampling vial passed into the space from the open first end may be impaled on the cannula; at least one guide member mounted on or connected to the body for movement about at least one hinge located at or adjacent the first end characterized in that the at least one guide member is configured for movement between a guide position and a non-guide position, wherein: in the guide position at least part of a free end of at least one guide member extends into the second portion to reduce the effective size of part of the second portion to receive a tubular body of a maximum fourth diameter, and in the non-guide position all of the at least one guide member is located outside of the space, and in the guide position at least part of a free end of at least one guide member extends into the second portion to reduce the effective size of part of the second portion to receive a tubular body of a maximum fourth diameter, and in the non-guide position all of the at least one guide member is located outside of the space, and the at least one guide member and the body are configured so that the path of the free end of the or each of the at least one guide member as the or each of the at least one guide member moves about the respective at least one hinge between the guide and non-guide positions clears the body and extends through the first end.