It officially began on Friday when the Duke of Edinburgh died, and will last up to and including his funeral on April 17.
What does this mean?
The Queen has approved a recommendation by Prime Minister Boris Johnson for a period of national mourning.
It means Union flags will be flown at half-mast on royal residences, Government buildings, Armed Forces establishments and at UK posts overseas for the next week.
Union flags at royal residences and on Government buildings were lowered to half-mast on Friday and will stay that way until 8am on the day after the funeral.
Public services and any services related to the Government response to the pandemic will continue as normal and people will be able to access information and services online as necessary, guidance issued by the Cabinet Office states.
No. The guidance says there is “no expectation for businesses to close during the mourning period unless they wish to”.
It says it is a decision for individual organisations.
Many businesses in England such as non-essential shops and outdoor hospitality are due to reopen on Monday, having been closed for months in the third national lockdown.
The guidance states that businesses might want to make arrangements for observing the national one-minute silence at 3pm on the day of Philip’s funeral.
What about sporting events, will they take place in this period?
This is also something which is at the discretion of organisers, the guidance states.
They suggest that organisers of sporting fixtures might want to consider using black armbands and observing a silence before matches are played.
Some sporting bodies are in discussions regarding plans for Saturday’s fixtures to avoid a clash with the funeral.
The Football League has announced that matches scheduled to begin at 3pm will be rearranged, as will Premiership rugby fixtures.
The Football Association, Premier League and the England and Wales Cricket Board are all in dialogue with the Department for Culture, Media and Sport regarding arrangements while the Women’s Six Nations is awaiting guidance, the PA news agency understands.
The British Horseracing Authority will also hold discussions regarding its own plans.
Can I lay flowers in tribute to Philip?
While floral tributes would normally be an expression of sorrow and appreciation on the death of a major figure such as the duke, people are being asked not to lay flowers, candles or messages in public spaces or at royal residences.
The guidance asks that people do not do so in order to comply with coronavirus restrictions currently in place limiting gatherings, and to prevent the spread of infection.
What can I do instead?
It is suggested that people could consider making a donation to a charitable organisation with which Philip had been associated.
The guidance states that would be a “fitting way of paying tribute to his remarkable legacy”.
A list of such organisations are on the royal family’s official website, where there also an online book of condolence.
There are no physical books of condolence available in public buildings – due to Covid-19 restrictions.
Will the royal family still carry out public engagements?
The royals will observe two weeks of what is known as royal mourning, starting from Friday when Philip died.
Engagements will continue appropriate to the circumstances, a senior royal official said.