Over the months, this evolved. We dropped the process ideas and focussed on the concepts, fleshing them out, adding Value and then Context.
We tried several configurations - not just the turtle diagram - including considering Change as a central, or primary concept. Eventually we realized that broke the model, and we settled back on the turtle.
The dice at that bottom are the latest version of the BACCM, showing all six core concepts and their relationships. They were a big hit at BBC 2013 - and they're useful too.