He illuminated the team display with neat footwork, clever offloads and smooth passing - not to mention a try in each half that, along with 16 points from fly-half Ronan O'Gara, helped the tourists home.
Henson was sparkling in the back division. His delayed pass to Geordan Murphy was perfect, Southland were stretched, infringed at the breakdown and O'Gara booted the Lions ahead.
Denis Hickie then sliced through a disorganised Southland defence and Mark Cueto took the ball to within a metre of the line.
It came back slowly, giving Southland a chance to reorganise, but Henson produced another of his exaggerated steps to create half a gap and then power over for the opening try.
The Lions then needed to crank up the pressure and pull clear, but were unable to do so before half-time.
Apanui slotted one penalty but missed two others in the first half and the Lions will have been frustrated at only carrying a 10-3 lead into the interval.
Life got worse for the visitors immediately after the restart as Southland pinned the Lions back into their own 22 and flanker Hale T-Pole drove over from the lineout for a converted try which levelled the scores at 10-10.
Woodward made immediate personnel changes. Having already brought on heavyweight prop Andrew Sheridan, Tom Shanklin came into the centre, Chris Cusiter replaced Gareth Cooper at scrum-half and Gordon Bulloch took over at hooker from Andy Titterrell.
Henson and Shanklin combined brilliantly and Cueto was all set for a try when T-Pole pulled off an astonishing one-handed interception to save Southland.
The Lions managed to keep the pressure on and after Martyn Williams had driven the ball to within touching distance of the try-line, O'Gara found Henson who straightened, barged through the tackle of Faolua Muliani to score under the posts.
The tourists then made a definite tactical switch, opting to kick for territory more often and it helped them open a winning cushion as O'Gara slotted two penalties.