The Undercover Policing Inquiry has ruled that, in order to encourage witnesses to give full and frank evidence, it will invite an undertaking from the Attorney General that they will not be prosecuted based on the evidence they give to the Inquiry. The Inquiry declined to go further and to request an extended undertaking which would have protected non-state, non-police core participants from being prosecuted based on any evidence given by anyone; the issue will be kept under review.
Further details here: https://www.ucpi.org.uk/wp-content/uploads/2016/05/160526-overview-note-undertakings.pdf and https://www.ucpi.org.uk/wp-content/uploads/2016/05/160526-ruling-undertakings.pdf
Alex Bailin QC represented the non-state, non-police core participants instructed by Tamsin Allen of Bindmans LLP.