I looked up Chilcot in Wikepedia and here is what I found.
Re his part in the earlier Butler report:
He is described as "a mandarin with a safe pair of hands", though some doubt his forensic skill. International lawyer Philippe Sands is reported as saying "Having some familiarity with Sir John's questioning ... it is not immediately apparent that he will have the backbone to take on former government ministers." Sands also commented specifically in The Observer, on Sir John’s questioning of attorney-general Peter Goldsmith during the Butler inquiry:
So he was an obvious safe choice to do the full GB set up inquiry and whitewash the establishment.
Again from Wikepedia.
On 15 June 2009, the then British prime minister Gordon Brown announced that Chilcot would chair an inquiry into the Iraq War, despite his participation in the discredited secret Butler report. Opposition parties, campaigners and back bench members of the ruling Labour Party condemned the decision to hold the inquiry in secret and its highly restrictive terms of reference which would not, for example, permit any blame to be apportioned. In 2015, Chilcot was criticised as the Iraq Inquiry remained unpublished after six years. Head of the UK civil service Sir Jeremy Heywood said the inquiry had repeatedly turned down offers of extra assistance to help speed up the report. Chilcot is paid £790 a day as head of the inquiry.
Sickening. the long suffereing families who lost sons and daughters in the war are not top of Chilcot's to do list. The establishment must be saved any embarassment at all costs..