My own rule has always been to use surnames for party leaders, Thatcher. Kinnock, Corbyn, May, etc, etc. Any familiarity is just wrong.
First it was 'Boris'. Then it was 'Rishi'. And now it's 'Kemi.' Am idly wondering why this is the case (populism or just unusual 1st names?) and whether the Conservatives will ever again elect a leader who isn't rapidly and routinely referred to by their first name in the media?