The Queen attends an Armed Forces Act of Loyalty Parade at Holyroodhouse on June 28 in Edinburgh, Scotland.

A version of this story appeared in the September 2 edition of CNN’s Royal News, a weekly dispatch bringing you the inside track on Britain’s royal family. Sign up here.

London CNN  — 

We’re back, royal readers, and just in time, with the announcement Monday of Liz Truss as the new leader of the governing Conservative Party – and consequently, the country’s next prime minister. As you’ll recall, the Queen and politics don’t usually mix, but she is involved in the transition, so let’s break it down.

As head of state, the appointment of new prime ministers is one of Elizabeth II’s core constitutional duties, along with the State Opening of Parliament and signing parliamentary bills into law. Truss will be the Queen’s 15th prime minister when she takes over from Boris Johnson on Tuesday.

video thumbnail truss PM speech
See the moment Tory Party announced Truss won leadership
06:20 - Source: CNN

Normally, the practicalities are straightforward. In a nutshell, the outgoing PM makes a statement outside 10 Downing Street and then heads off to Buckingham Palace for a final farewell audience with the monarch. Shortly after, their successor travels over for their appointment. All in all, it’s relatively quick, taking around half an hour. However, this time … not so much.

The sovereign had intended to interrupt her vacation in Scotland and return to London to appoint the new PM. But in a break with royal tradition, Buckingham Palace announced Wednesday that the 96-year-old will not be making the 1,000-mile round trip, with the outgoing leader and his successor traveling to Balmoral on Tuesday instead.

According to a royal source, the decision to hold the two audiences at her Scottish country residence rather than at Buckingham Palace – for the first time in her 70-year reign – was made to provide certainty to the Prime Minister’s diary. The source told CNN the decision was to avoid any last-minute alternative arrangements in the event the Queen finds herself experiencing any episodic mobility issues. As a result, Tuesday will likely be a more protracted event due to the distance between London and Balmoral and the logistics involved.