Not sure if this is quite right.
I would have said the cave after first couple of pitches is where you have marked 'start of traverse' and the hansom cab stance is roughly where you have marked lower '60m ledge'.
The upper pitches are very foreshortened in the photo.
When I did it I just followed SMC guide and not Gary Latter's 5b variation which looks good.
I noticed the other topo uploaded here starts from the very lowest rocks rather than the ledge higher up which might confuse things.
Ahh, the debate continues...

I used the SMC guide too, the photo was taken at the end of the first 50m pitch, the second 50m pitch went to the same height as the cave marked and would not reach the cave in the gully (or the one above, 3 potential caves!) I was confused as to what a "Hansom cab," was, and on googling, thought it meant the stance shown, where there is an overhanging stone at the edge. It may also mean the stance you refer to, with its overhanging rock.... From what I have called the cab stance to the 60m ledge is a great pitch, as is the one above. There were crampons scratches and chalk on both, but that may be other lost parties....?

Don't follow this photo topo!
As per the previous comment, what is marked as 'start of traverse' is actually the cave belay. It is possible to traverse the poorly protected 6" wide grassy ledge here, but I don't recommend it!
What is marked as the first '60m ledge' is indeed the Hansom Cab stance with a large comfortable block belay. It is easy to see the 15m grassy traverse from here, which is around 3ft wide rather than 6".
The route of our mistake was using the pitch length descriptions from the SMC guide up to the cave belay, thus convincing ourselves that we should be on the traverse pitch. I recommend picking a line up to the cave belay and then following the route descriptions from here which should be fairly straight forward.