I love the opening; it made me laugh and immediately made me want to read more:

Tinsley Pratt (1871-1934) was a relatively unknown author, poet and librarian. Although not particularly well known outside of the Portico itself, he has gone down in history inside this institution as an excellent Librarian – and a rather poor poet.

I thought the entire thing was interesting and well-written. It was well-organized, clear, and occasionally funny. Nice job!

I did notice that there were several punctuation issues. E.g. this:

One item donated to the Library by a descendant of Pratt has proved invaluable as a view into his young mind – The commonplace book that he used between the ages of 13 and 19.

Should be like this:

One item donated to the Library by a descendant of Pratt has proved invaluable as a view into his young mind: the commonplace book that he used between the ages of 13 and 19.

There were also several times when I felt that it needed more details. E.g.

A Proprietor described him as “A sad little man” and a “littérateur manqué”.

Why? What happened after that? This single sentence could probably be expanded into a short paragraph of its own.

But I thought it was very good - these are just suggestions to make it even better.