From meeting the King to checking out the nuclear bunker - what does a new PM's first 24 hours look like

For whichever of the two men emerge as the new PM, the next day will start in their constituency and, end in Downing Street, via Buckingham Palace, their campaign headquarters and the nuclear bunker.

These are some of the key aspects and happenings of the first 24 hours of any new Prime Minister.

In order to become Prime Minister, they must be appointed by the King. Therefore the winner of the election must head to Buckingham Palace to be formally given the job before they can start getting on with governing.

Sir Tony Blair, who was swept into power via a Labour landslide in 1997 recalled years later how he tripped on a rug and “practically fell into the Queen’s hands” when he went to the Palace to be appointed.

Within hours of entering No10, they will also visit the nuclear bunker underneath the residence. Within there, it has beds, food supplies, communications facilities and a television studio from where the prime minister can broadcast to the nation if the national infrastructure is still up and running.

A former staff member for Theresa May once recalled that when they were shown around the bunker they were told that Cherie Blair did not like the rudimentary furniture in the prime minister’s bomb-proof living quarters and demanded it be changed.

Staying on the topic of a possible nuclear apocalypse, one of the most important meetings the new prime minister has is with the Chief of the Defence Staff, a position currently held by Admiral Sir Tony Radakin.

During the meeting, the Chief of the Defence Staff will explain the process of writing letters of last resort with instructions for the commanders of Britain’s Vanguard Class of nuclear-armed submarines. The letters, which must be hand written, are set to instruct officers on what to do if Britain has fallen victim to a nuclear attack and the prime minister is either dead or incapacitated.

The Chief of the Defence Staff will explain the options, which are said to include retaliating, not retaliating, using their own judgement and putting themselves under the command of the US, if the Washington government is still functioning.

The unopened letters of last resort written by the previous PM must also be destroyed immediately. The incoming Prime Minister is likely to be advised to take their time and not rush into writing the letters straight away after a sleepless night.

Any new PM is also expected to take calls from various world leaders. However, while some are congratulatory, others are more opportunistic, looking for favours.

One former prime ministerial adviser said: "They tend to be very repetitive, mainly about admin, but some of them will take the opportunity to lobby the PM for something they want."

The incoming Prime Minister is expected to choose an office within Downing Street. Margaret Thatcher had her office on the first floor of the building, while Gordon Brown had his office in No. 12.

David Cameron moved his office to an ante-room adjoining the Cabinet room, and it has remained there ever since.

Any outgoing prime minister will then have left the scene, perhaps only an hour or so earlier, and will have written a note to their successor wishing them luck.

Thatcher famously quoted St Francis of Assisi saying "where there is despair, may we bring hope", while Cameron talked about rebuilding trust in politics and Theresa May promised to tackle the "burning injustices" the country faced.

Once the speech is over, the new prime minister will walk through the black door of their new office and home, applauded by a vanguard of No. 10 staff lined up on either side of the entrance hall.