Thanks tuc. Unfortunately I can find no link to the BoI for TG577, but hope that others more adept at t'internet might find some link to it, if only a summary. I'm afraid that wiki is not the best authority on anything, simply the most convenient. Your point about the AAIB's role in BoI's is well made. They do not conduct the Inquiry, the RAF Board does. They merely contribute what the Board asks them to and, as you say, a great deal of that may never appear in the final RAF published report. Hence the call for an independent military investigator "sistered" to the AAIB.