I've just come from a presentation by the Department of Energy and Climate Change (DECC) to members of the Renewable Energy Association.
An update on the ROC banding process was provided by Olivia Knibbs who is a member of the Renewables Obligation team at DECC:
"the banding consultation will be published shortly and I do mean shortly"
She also confirmed that it was still DECC's intention to pass the new bands into legislation by April 2012, although she acknowledged that the timetable was now "squeezed".
So, still no firm timescale, but at least DECC seems aware of the urgency.