Albert Halstead was an American diplomat who travelled with Wilcox and Castle through the area in 1916. Apparently he was the U.S. commisioner in Vienna after World War I, and then was the consul general in Montreal from 1920-1928. (Boles)
Although I've never visited the pass it looks pretty strange on the map. Was Wilcox really at Halstead Pass in 1920 or so? Can you get down to the east? It's sure high??
David Henry visited the area in 2004. His opinion is as follows: "I was recently at Panther Lake on an extended backpacking trip and tried to locate Halstead Pass while I was there. There is no pass located at the location indicated on the map. There is a cliff band along the eastern slope which is not passable. There is however a low col to the south and west of Panther lake which could be traversed. I viewed this slope from both the east (Panther Lake) and the west (Bonnet Peak) and it looks possible, but there is no trail and it would require a very steep scree ascent on the eastern slope. In any case I would not classify it as a pass."
"Your site’s description of Halstead Pass encouraged a friend and I to do a traverse across the area in September. Our trip took us up the Panther River and over the low col to the south west of Panther Lake into the Valley of the Hidden Lakes. We then followed the Valley north to Douglas Lake and ultimately exited at Lake Louise."
Nolan Hindmarsh visited the area in 2005 and passed along these observations: "The description of the pass offered by David Henry was entirely accurate. The map location has large cliff bands on the eastern slope which are not passable but the low col to the south west of Panther Lake can be traversed. It is a steep ascent on the eastern slope and a more moderate descent on the western side but the route is all large scree with no cliff bands along the way. There is no trail to follow.
"The map location for “Halstead Pass” is actually a cirque cut into the eastern slopes of the Valley of the Hidden Lakes. It looks passable when you’re in the valley but a glance over the top would put a quick end to that idea. The real traverse point to the south is practically hidden from view in the valley. You would almost think that whoever located Halstead Pass on a map had viewed “it” from the valley but never climbed up to look."
Brian Larman reports in September, 2007, "There appears to be a bit of confusion as to where exactly Halstead Pass is located, due to the error on the map, but the written accounts are pretty spot on.
"The description is accurate, the cliff band would be impossible without technical climbing, and the other side isn't much better, ridiculously steep scree ending in what I could only imagine is a horrible pit with teeth, similar to that desert scene in Star Wars. The col where the pass really is is definitely passable, though really steep and loose. There was a significant amount of snow when we were there, July 15th, which actually helped the scramble a bit, especially on the lower part of the very steep section.
"On an interesting note, there was a small lake up at the top, which apparently wasn't there last year. I imagine it was due to the amount of snow still left, and might no longer be there as I write this, but a pretty cool feature nonetheless."