I have finally found a book that is helping me to make sense of the Scafell Caldera. Cumbria Libraries have multiple copies. I found it first as a Google Book with this search
https://books.google.co.uk/books?id=cjwfT_nDvLQC&pg=PA53&lpg=PA53&dq=paul+gannon+scafell+caldera&source=bl&ots=TShZ0eZEtr&sig=ACfU3U1jaN3oIxGGNNFVKZ0JfiYXTx_VrA&hl=en&sa=X&ved=2ahUKEwj0iYLaoIjlAhVhoFwKHVRYDkcQ6AEwAnoECAkQAQ#v=onepage&q=paul%20gannon%20scafell%20caldera&f=false
He has sorted out for me the Borrowdale Volcanics. Apparently there were two phases - the Lower Borrowdale Volcanic Group and the Upper BVG. Lower was lava and Upper was explosive. Upper was the time of the Scafell Caldera. The explosive erruptions produced a lot of dust and ash which fell to earth, settling in lagoons in the caldera and becoming sedimentary rock. It began to make sense of this document
http://nora.nerc.ac.uk/id/eprint/3234/1/RR01007.pdf . As we were going up Crinkle Crags, I decide to look out for the tuffs listed on page 21 of Geological Survey document. Here's the approach to the Bad Step
I picked up the rock below in the vicinity. It is certainly weathered pink but whether it is really a Bad Step tuff as opposed to any of the other identified Crinkle ones I'm not qualified to say. There must have been a lot of individual eruptions in the area.
