Ministers have taken charge of plans for the days following the Queen’s death for the first time, leading a secret Whitehall exercise to prepare for ten days of national mourning.

Elizabeth II is Britain’s longest serving monarch, but at some point her reign will come to an end – and the outpouring of grief over her passing will be immense.

“It won't just be sombre dress and a minute of silence at sports games — it'll be a punch to the gut of the national psyche,” says Business Insider.

While there is some level of uncertainty as to what will actually happen in the immediate aftermath of her death, some aspects have been meticulously planned.

What is Operation London Bridge?

The first plans for the Queen’s death, codenamed ‘London Bridge’, have been in place since the 1960s, but were refined around the turn of the century.

Like with the death of her father King George VI in 1951, once her death has been confirmed by her personal physician, currently gastroenterologist Professor Huw Thomas, the prime minister will be notified by the code “London Bridge is down” on secure lines, to avoid any preemptive leak.

The Foreign Office’s Global Response Centre will alert the 15 governments outside the UK where the Queen is also the head of state, and the 36 other nations of the Commonwealth for whom she has served as a symbolic figurehead.

In keeping with tradition, once news of her death has been formally announced, a footman in full mourning dress will pin a black-edged notice to the gates of Buckingham Palace detailing a ten-day mourning period. Simultaneously, the palace website will post a similar message on a single black homepage.

How will the press be notified?

For many years the BBC was told about royal deaths first, “but its monopoly on broadcasting to the empire has gone now”, says The Guardian. Today the announcement will go out on a newsflash to the Press Association news agency, and the rest of the world’s media at once.

Almost every major news organisation have pre-recorded films, articles and news segments read to go. The Times is said to have 11 days of coverage set to roll out, while Sky News and ITN, which have been practicing for years substituting the name “Mr Robinson”, have signed contracts with royal experts who will speak exclusively on their channels.

Commercial radio stations will be alterted through a network of blue “obit lights” which are supposed to light up in the event of national emergency. This gives DJs notice they will be switching to a special news bulletin and a reminder to play inoffensive music in the meantime.

What about the BBC?

The broadcaster regularly practises how it will respond to the death of the Queen and other senior members of the royal family.

At the BBC, the ‘radio alert transmission system’ (Rats), will be activated. A cold war-era alarm designed to withstand an attack on the nation’s infrastructure, the Daily Mail describes the system as “a near mythical part of the intricate preparations for the death of major royals that the BBC has held since the 1930s”. The Guardian says some staff also refer to it as “royal about to snuff it”.

"Like all news organisations, the BBC has plans in place," a source told the Sunday Times in 2011. "We provide training to ensure staff understand what would be expected."

It was during such a training exercise last year that a BBC Urdu journalist, overhearing the rehearsals, prompted a brief global media frenzy when she mistakenly tweeted that the Queen had died. The corporation issued a swift apology and Buckingham Palace broke its usual protocol of not commenting on speculation about the health of the royal family by confirming the monarch was indeed alive and well.

Hoping to avoid a repeat of another faux pas committed in 2002, when BBC newsreader Peter Sissons wore a burgundy tie to announce the death of the Queen Mother, presenters have been instructed to have a dark-coloured suit and black tie on standby.

The BBC, along with all major news channels, have pre-recorded packages on the Queen's life ready to be aired "at a moment's notice", says Business Insider. If she passes away during the night, her death would reportedly not be announced until 8am, after which her portrait will be displayed on the screen accompanied by the national anthem. The BBC is also expected to suspend all comedy shows until after the burial, the Daily Mail understands.

The funeral

Funerals for senior members of the royal family are organised years in advance, and have been overseen by the Duke of Norfolk since 1672. "Detailed plans are laid for the Queen's funeral, and for the sequence of events - both in Britain and the 15 other realms - by which the new king is shown to the people," says the Daily Telegraph.

As monarch, the Queen is automatically accorded a state funeral and banks and the London Stock Exchange will be closed on the day, which is expected to fall 12 days after her passing. The service will be led by the Archbishop of Canterbury, currently the Most Rev Justin Welby, and will be attended by the royal family, politicians and heads of state from across the globe.

"The Queen herself is known to have a relatively sanguine view of the inevitability of her own demise" and has even planned elements of her own funeral, says the Daily Beast.

Her coffin will lie in state at Westminster Hall before being processed to either Westminster Abbey or St Paul's Cathedral for the service, according to Royal Central. Like many monarchs, it is expected that the Queen will be interred in St George's Chapel at Windsor Castle, where her mother and father, King George VI, are buried. "The Queen and the Duke of Edinburgh would be buried side-by-side," adds the website.

Was last week a practice run then?

Not really. On Thursday, David Lidington, Theresa May’s de facto deputy, chaired an extensive meeting that also included Home Secretary Sajid Javid; leader of the Commons Andrea Leadsom; and Scottish Secretary David Mundell.

The exercise, dubbed “Castle Dove”, focused on “D+1”, the day after the Queen’s death, with ministers deciding when the prime minister would make public statements. It took place in the Cabinet Office room where the COBRA emergency committee meets and was the first time ministers have been directly involved in the Queen’s funeral planning.

The Times says the exercise “was not prompted by specific concerns about the Queen’s health, but it came in a week that the 92-year-old monarch missed a service at St Paul’s Cathedral because she was unwell”.

One Cabinet minister told the paper: “Things have clearly been stepped up because of the ageing process.”

The succession

After the Queen's passing, the Prince of Wales will automatically become king, barring any unforeseen circumstances. However, he won't necessarily become King Charles as royals can choose from any of their given names, meaning he could become King Philip, Arthur or George. There is no timetable for a coronation and it could happen up to a year after his accession.

Prince Charles has increased his royal workload since the Queen cut back on foreign visits in 2013 and appears to be slowly taking over the reins. However, polls have consistently shown that he lacks the public support and admiration afforded to his mother. A survey in April 2017 found that only 53 per cent of people said they liked him, compared to 77 per cent for the Queen.

Does anyone else have a funeral codename?

The most recent royal state funeral was that of the Queen Mother in 2002. Operation Tay Bridge had been planned for years and saw a million people line the street and another 200,000 file past her coffin as it lay in state in the Palace of Westminster.

Tay Bridge also provided the template for Princess Diana’s funeral five years earlier.

Prince Philip, who turns 96 in June and has recently been in hospital to have a hip replacement operation, has had plans for his funeral “intensified” in recent years, says the Daily Mirror.

Known as ‘Forth Bridge’, which he opened in 1964, Philip has refused the offer of a state event preferring instead a private service at St George's Chapel, Windsor, in the style of a military funeral.

Apart from ruling monarchs or high-ranking members of the royal family, only Sir Winston Churchill has been afforded the honour of a state funeral in the last century.

Planning for 'Operation No Hope' began in 1953, when Churchill was still prime minister, 12 years before his death.

The Mirror says it was the Queen's wish that he be given a state funeral thanks to his heroics as a wartime prime minister.

The paper says the procession was planned down to the second and at the time it was recorded as the largest state funeral in the world.