‘Unite or die’ - Rishi Sunak's message to Tory MPs before he meets King Charles III

As the United Kingdom hopes for better days ahead with a third leadership change within weeks, Indian-origin Rishi Sunak's rise to the prime minister's post has prompted congratulatory messages from across the word.

United States President Joe Biden has called it a "groundbreaking milestone" with the United Kingdom set to get a leader of colour. Sunak is the first UK PM of South Asian heritage. He is also set to be the youngest premier of the country in nearly two centuries.

Soon after he catapulted to the top post, the 42-year-old told Tory MPs to "unite or die" at a closed door-meeting, as per news agency AFP.

Sunak will be taking charge officially on Tuesday after meeting King Charles III, as per protocol.

Here are ten updates on Rishi Sunak's feat and UK leadership change:

1) Liz Truss - who took charge in September first week - is set to hold her final cabinet meeting on Tuesday morning (local time) at 10 Downing Street. She would then head to meet King Charles III and officially resign, reports said.

2) Sunak's highly anticipated meeting with the monarch is expected after this.

3) After Truss's resignation on Thursday, Sunak had emerged as a frontrunner with a huge backing. Even as his contenders emerged in former PM Boris Johnson and Penny Mordaunt, he managed the feat on Monday when both of them dramatically dropped out of the leadership race within hours.

4). In his first address as the PM elect, he clarified that his "utmost priority" would be "stability and unity" for the United Kingdom.

5) Uniting the Conservative Party - which has historically seen differences - would be a big challenge for the 42-year-old apart from steering the UK economy in the right direction.

6) Even as there have been calls for election, the UK is not due to vote till January 2025. Sunak is the latest leader who lacks a direct electoral mandate.

7) All eyes would now be on Sunak's cabinet. It is yet to be seen if he would keep Jeremy Hunt as Chancellor of the Exchequer amid the pursuit to calm markets. On Monday, as per a Bloomberg report, talks were held over his cabinet as he said he would lead a "government of all the talents".

8) As Tories were forced into the second contest since summer, rival Labour leaders have not taken very kindly to the changes. "The Tories have crowned Rishi Sunak without him saying a word about what he would do as PM. He has no mandate, no answers and no ideas," tweeted Angela Rayner, deputy Labour leader.

9) Sunak is the son-in-law of Infosys co-founder Narayana Murthy. "Congratulations to Rishi. We are proud of him and we wish him success. We are confident he will do his best for the people of the United Kingdom," Murthy said in his first remarks, reacting to the developments.

10) Calling Sunak a "living bridge", Prime Minister Narendra Modi congratulated Sunak on Twitter and said he is looking forward to "working closely together on global issues." "Special Diwali wishes to 'living bridge' of UK Indians as we transform historic ties into modern partnership," he tweeted as India celebrated the festival of lights.