Joseanne
What makes me laugh is that there were so many complaints on here about calling the PM by his Christian name, Boris, and now we are nearly all calling Sunak by his Christian name, Rishi! Is that an omen?
I think the name 'Boris' and always calling him that made him sound like a cuddly bear not the lying git that he is - so it rather softened the tone when referring to him, something like that.
Also, it was a leftover from his days as mayor of London, rather like Ken Livingstone you only had to say his first name when referring to anything political and everyone knew who you meant.
Maybe Rishi rolls off the tongue easier than Sunak, BTW as a Hindu it's his first name not Christian name!