Here is a "catch-up" on a number of ongoing inquiries -
Independent Inquiry Child Sexual Abuse - website - set up 7 July 2014 but reconstituted in February 2015 as a statutory inquiry under the Inquiries Act 2005 - Since 11 August 2016, chaired by Professor Alexis Jay. The inquiry has issued several investigation reports as well as an Interim Report to Parliament (April 2018). The Inquiry website states 'although our programme of public hearings is now complete, work is ongoing and all information gathered with inform the Chair and Panel's recommendations in the Inquiry's Final Report.'
Undercover Policing - website - set up 12 March 2015 - first Chairmanwas Sir Christopher Pitchford who stepped down for health reasons and, in 2017, was replaced by Sir John Mitting. See the Inquiry's 10th Update Note (July 2021).
Jermaine Baker - website - set up 14 February 2020 - Chaired by Clement Goldstone QC - the inquiry is now adjourned until 6 September 2021 when closing submissions will be heard.
On the subject of inquiries generally, the Institute for Government has published several articles.
There is no doubt that inquiries are lengthy, cumbersome, beset with legal difficulties, enormously expensive, and follow-up on recommendations is too often inadequate. Are they worth it? That question was explored by the Institute for Government back in 2013 - see here. I leave it to you to judge.
As we know, the Prime Minister has promised an inquiry into the Covid-19 pandemic. The precise scope of this remains to be seen and the process of setting up the inquiry has not yet commenced. See The coronavirus inquiry | The Institute for Government.
How long such an inquiry will take remains to be seen and it is pointless trying to guess. Several years to a final report seems likely unless the inquiry is somehow able to act with extraordinary speed and produce an early report with recommendations on any urgent and immediate action considered to be necessary.
8 August 2021