should in "who am I that I should tell this one and that...?"

[optimistic pessimist]

Hi all,
The following passage is an excerpt from a novel by S. Maugham. (source: The Happy Man - Home reading lessons (google.com)

"...And life, unfortunately, is something that you can lead but once; mistakes are often irreparable, and who am I that I should tell this one and that how he should lead it? Life is a difficult business and I have found it hard enough to make my own...

I would like to ask the use of "should" here. What does this "should" imply? Is it a kind of British usage?

OP

 

[GoesStation]

Maugham wrote in British English, of course, but the subject sentence reads like very formal, old-fashioned cross-Atlantic English. The sentence, simplified, means "How dare I tell someone how to lead their life?"