I am watch a history show. The presenter says
George III ruled for 60 years - one of the longest reigns of any British monarch.
I feel she wants to compare the duration of George's ruling to all other monarchs.
But she has already said he is one of the longest, is 'of any British monarch' still necessary?
If he is the longest, then 'one of the' is redundant.
What does this 'of any British monarch' try to say?