From the base of the bush (upstream of the forks draining the saddle), follow the orange triangles steeply uphill until they descend into a small gully, not marked on the map. The markers now become sporadic, and it’s basically up to you to follow the gully up. This is the slight ‘v’ in the contours shown on the topomap to the east of the gridline which bisects the saddle. As such, you’ll have to abandon the gully at some point before you hit bluffs and scree, and cut 500m to your right to find David’s Saddle. I walked this section in thick fog, and can confirm that with careful map reading it is possible to find the saddle. In clear conditions it should be clearly visible above. The descent of the Matakitaki side of David’s Saddle is steep and loose: follow the base of the ‘V’ shaped ravine all the way to the valley floor, surfing a tide of loose scree all the way.
Note 2018: depending on snow conditions, it could be potentially easier to descend via rocky face on left side of the gut (go quite a long way left). There may be a bit of easy down climbing required, but mostly fairly straightforward, and avoids waterfalls lower down the creek, and rock falls on the right side.
Note: Described in the reverse direction to your journey
Climb up through tussock along stream to base of rock. From here, climb onto rock on right hand side (true left of stream). Do not attempt to use the stream, as it soon has waterfalls and true right has a lot of loose rock (rocks were falling from above). Climbing up the rock face is easy - solid and lots of foot and hand holds with a distinct foot pad in places. Follow the rock and tussock all the way to the top of the ridge, where it is easy to drop down into the middle of the true saddle. Descent down the "scree" on the northern side is straightforward - it has large pieces and isn't very loose, so doesn't move much. Stay slightly to the right, to intersect with a line of small cairns dotted on top of the larger rocks. When these run out, there is a "V" of loose rock and tussock slightly to your left - use this to descend to the tussocky plateau. The plateau consists of larger tussock interspersed with speargrass. Keep descending on the left edge of the thicker vegetation/scrub until another large rock and cairn is reached. From there turn hard right (90o) towards the trees, where the first orange triangles are spotted. Stay away from stream on the left - it'll soon turn into a large waterfall! In the trees, a nice looking, marked track sidles across to a creek, from there it is a steep descent down. At one point the track is higher above the stream and the triangles seem to end - climb down into the creek bed and down for a few meters, where you should see triangles continuing on the true right. Back into the trees on the far side, the track becomes easy to follow down to the D'Uville Forks.