It's called reputation; the AAIB has over the years produced many reports of very high quality which have changed and improved the way planes are made and the way we fly. They deserve our trust.
Once again, trust doesn't have anything to do with investigations. We are talking about facts. Investigations' raw info is to be publicly available to ensure transparency.
What kind of reputation do you refer to when considering none of your "high quality" reports has been released following the dozens of concorde's tires accidents, especially when this is seriously recommended by the NTSB ? As far as I know, one's reputation is presumed good until it's no more...