There is a fairly well-worn process that senior civil servants must guide a newly-elected prime minister through during their first 72 hours in the role. 

After a prime minister is appointed by the monarch they often return to make a speech outside the front door of No.10 Downing Street. Once they enter through that famous door, the real business of government begins. They will be clapped into the building by the No.10 staff, greeted by the cabinet secretary and then will receive pre-prepared civil service briefings. These briefings cover everything from living arrangements for the prime minister and their family, to the ministerial appointments process, urgent decisions on key policies, important protocols, security and intelligence information, and the nuclear deterrent. 

Alongside these, the new prime minister is immediately launched into many rounds of phone calls with international leaders. The order in which these early tasks are completed will partly depend on external priorities, partly on how the new prime minister wants to tackle them and partly on how each day pans out. Getting through it all can be an exhausting process, particularly following a gruelling election campaign, and the pressure of media and public anticipation usually means they want to be seen to be energetically embracing their new role.

The first 72 hours provides an early lesson in how huge the job is and how extensive the demands on their time will be.