The naming of the passes of the Southern end of Narrow Neck, near what is labeled most maps as Duncans Pass and Taros Ladders, seem to get quite muddled up. My understanding is as follows:
There are two routes down to the valley floor from Clear Hill - One down the spikes and another down a ramp.
The route down the current spikes was originally discovered (first use by a bushwalker, though Fred Eden descended Narrow Neck in the 1890s, but the exact route taken is unknown) by Frank Duncan in 1928.
The day after Duncan's route was discovered, a party which included Alan Rigby (who was instrumental in saving Blue Gum Forest), discovered a pass that did not involve descending a rock face.
The following is an explanation of the information obtained from multiple maps of Narrow Neck over the period 1919 - 1932.
A map of Myles Dunphy's from 1919, shows a portion of what we now call Dunphy's Pass named as "The Wallaby Parade". There were no passes at the end of Clear Hill shown (Named "Clear Head or Clear Hill" at the time).
A later map of Dunphy's, from 1930, shows a single pass of Clear Hill beginning on the Western side and snaking around the nose the the Eastern side before turning back and heading South towards Debert Knob (Later changed to Mt Debert). This seems to follow the route of the ramp. I can not determine the name given to the pass as it seems to be crossed out. Any guesses?
Another Dunphy map from 1931 shows two names given to a pass down from Clear Hill. The first is "Rigby Pass" but it appears to be crossed out. The second is listed below it as "Duncans Pass". I can not however determine from the map (a copy of the original stored on a tiny 'aperture card') what route the named pass takes. I assume that it would follow that of Dunphy's previous 1930 map but that may be an incorrect assumption. The crossing out and renaming of the pass seems to indicate a name change. When the name of a feature changed, Dunphy usually crossed out the old one and wrote the new one next to it, so that references to the old feature could still be identified. This indicates that originally the pass (going down the ramp) was called "Rigby Pass" until it was later changed.
Finally, a Dunphy map from 1932 depicts a single route down from the end of Narrow Neck, identical to that from 1930, along was named "Kangaroo Parade" on the Western side and "Duncans Pass" on the Eastern side.
From this information, it seems that the route found by the Rigby party (down the ramp) was the one mapped by Dunphy, not Duncans route down the cliff, but it was named Duncans Pass!
In 1933, a set of two wire ladders were installed down Frank Duncan's rock face pass by Walter Tarr (hence Taro's Ladders), allowing for an easier descent (he described it as being placed "for the convenience of weaklings"!). They were later replaced in 1940 by the current spikes after the ladders were burnt in a 1939 bushfire.
A map of Narrow Neck produced by the Australian Section Imperial General Staff in 1942 (On page 18 of "The Passes of Narrow Neck" by Keats and Fox) depicts the route of Clear Hill completely on the Western side, which is the route that Taros Ladders follow. It is however named Duncans Pass, correctly acknowledging the first bushwalking party to descend the route.
Jim Barrett, a bushwalker/historian who has written many books on the area, suggests in his "Narrow Neck and the Birth of Katoomba" publication that the pass discovered by Rigby was known as the "Wallaby Track". I am yet to find a map that refers to it as such, so I can't confirm Barrett's word. Maybe it was the result a mix up with the nearby Wallaby Parade, shown in the above referenced 1919 map?
He believes that the route of Clear Hill should be referred to as Duncans Pass, which is comprised of two separate passes. They are Taro's Ladder on the Western side and the Wallaby Track on the Eastern. His logic makes sense in that Duncan's party was the first bushwalkers to find a route of Narrow Neck in that area (ignoring the trip made by Fred Eden in the 1890s...), and so claim name to the route. The confusion arises in that some maps such as Dunphy's 1932 and Gangerang, and the current 1:25000 topographic, label the Eastern pass as Duncans Pass.
Michael Keats on the other hand, in his book written with Brian Fox, "The Passes of Narrow Neck", seems to offer a different opinion...
The section on the Clear Head Passes describes Duncans Pass being named after, and rediscovered by, Frank Duncan. The book then goes on to describe the pass being "to the left as you descend, 30 metres back from the Tarros Ladders" and that "no climbing is required". This, according to Duncans report attached above, is incorrect in that he did not rediscover the pass that does not involve climbing.
Further, the book states that this pass was referred to as "Wallaby Parade" (the name given by Dunphy a track beneath Glen Raphael as shown in the above maps) and lists it as an alternate name for Duncans Pass. This just confuses everything even more.
To answer my original question of 'Which one is Duncans Pass' I will say this:
1. The pass which descends Clear Hill on the Western, and now makes use of spikes which replace Taros Ladders, was discovered by a party involving Frank Duncan.
2. It would be logical to refer to is as Duncans Pass.
3. The other pass of Narrow Neck, descending on the East and involves no climbing, named on many maps as Duncans Pass, was discovered by a party involving Alan Rigby.
4. It was not discovered by Frank Duncan.
5. It does not make sense to refer to it as Duncans Pass
6. Another name such as Rigby Pass (crossed out on an above referenced map and my preference), Wallaby Track (suggested by Jim Barrett) or Gundungurra Pass (suggested by Wilf Hilder in a Bushwalking NSW Tracks and Access Report, 17th April 2007, on the passes of Narrow Neck) would be suitable.
I don't believe that the question has been fully answered, and so I will continue with some more research. Maybe Dunphys Journals from the period, as well as the original maps, map share some more light.
If anyone can add any information, it would be much appreciated. It would be interesting to know what names bushwalkers have used for the passes over the years between their discovery and the present day.