Covid inquiry: What is it and how will it work?

Boris Johnson has announced an independent public inquiry into the government's handling of the coronavirus pandemic.

He told MPs it would examine the decisions "in the cold light of day" and "identify the key issues that will make a difference for the future".

A public inquiry is a major investigation, launched by the government.

Its job is to respond to "public concern" about a particular event or set of events - such as the pandemic.

According to a leading specialist lawyer, it must ask three questions:

An inquiry has the power to make people appear as witnesses, and to provide documentation and material evidence.

At the end, the public inquiry usually draws up a report and makes recommendations to the government.

Previous high-profile public inquiries have included investigations into the UK's role in the Iraq war, the events of "Bloody Sunday" in Northern Ireland and the phone-hacking scandal.

The prime minister says he intends to launch the inquiry in Spring 2022.

He told MPs the delay was necessary to avoid putting too much stress on the NHS, advisers and government while there was the risk of a winter surge later this year.

The exact aims and remit - known as the terms of reference - will be announced closer to the start of the inquiry next year.

This is partly to allow time for the UK government to work with the devolved administrations in Scotland, Wales and Northern Ireland on the scope.

There is no time limit on how long inquiries can last but they often take years to complete. This is partly because of the huge amount of evidence that needs to be read.

The Chilcot Inquiry, which looked at the Iraq War, was published in 2016, seven years after it started taking evidence, while the Bloody Sunday inquiry took 12 years.

Dame Deidre Hine, who authored a review into the swine flu pandemic, told the BBC, "Looking at what will have to be the terms of reference and the ground it (the inquiry) has to cover, I can't see it reporting in less than two to three years."

The chair of the inquiry will not be announced until closer to the start date.

Ministers can appoint whoever they like to lead an inquiry but they must be independent from the government.

Judges are often used but sometimes other experts are chosen.

Whether the chair is a judge or not does not affect the legal powers of the inquiry.

Although public inquiries are independent, ministers have the power to sack the chair.

The chair can call whoever they want - whether they are witnesses to an event or people with a particular expertise.

Failing to turn up to evidence sessions or provide documents without a reasonable excuse is a criminal offence under the 2005 Inquires Act.

In England and Wales, it can lead to a sentence of up to 51 weeks in prison.

Inquiries are sometimes complicated by criminal investigations taking place at the same time. This can mean the chair is unable to call a witness because they are also involved in criminal proceedings.

Unless there are good reasons to hold sessions behind closed doors, it is likely most evidence sessions will be on TV and online. The prime minister confirmed that evidence will be given "in public, under oath".

The Leveson Inquiry into practices of the press - set up following the phone-hacking scandal - heard evidence from well-known figures such as Piers Morgan, Hugh Grant and Rupert Murdoch.

Some evidence sessions during the inquiry into the Iraq war were held in private either due to national security concerns or protect the identity of witnesses.

There are 11 currently under way - these include inquiries into the Grenfell Fire and the Manchester Arena bombing, as well as wider topics such as undercover policing and child sexual abuse.

It is up to the government whether to launch an inquiry.

According to legislation passed in 2005, ministers can set one up if they think "particular events have caused, or are capable of causing, public concern", or if "there is public concern that particular events may have occurred".