Glanced through a couple of those; they're really well produced.
I wonder if Dr.TDF would have agreed with that interpretation of the Speedwell Vent? The explanation of it in that particular walk begs the question as to why the whole of the volcanic outcrop is "brecciated" if the surrounding rocks aren't. Rocks are usually brecciated as a result of being within a fault zone, in which case outcrops of brecciated rock are usually linear. It also begs the question as to where the vent which supplied these volcanic rocks is actually to be found.
(I must do a bit of reading up about this one, when I get time.)