The 39 Steps - John Buchan 1915

I was reading an article recently about what the journalist considered to be one of Canada'a more successful Governor Generals, John Buchan.  Seems there is a new biography about him.  This caught me by surprise, as I remembered his name from a book I used to read years and years ago at my cousin's house, Greenmantle.  I checked him out on Wikpedia and, lo and behold, he is the author of a book called The 39 Steps, which is also the title of one of Hitchcock's well-known films.  Sure enough, the film is base on Buchan's novel.  What more, it turns out Buchan was a prolific author in his spare time.
Considering it was written in 1915, the book has held up well.  The story line is fast-paced and acceptably engaging.  The other side of the book that held my interest though, is the insight into the mind and way of looking at the world of a member of the British ruling class in the early 20th century.  I suppose what you see is the ideal of the British gentleman from the early 1900s - understated, brave, clever, determined, patriotic, but with the rough edge and "get it done" attitude of a colonial in Britain.
You can also see the prejudices and stereotypes of the time deeply ingrained in the book:  Jews, Germans, the rough but steady and dependable poor of the countryside (perhaps part of the colonial element, or left over romanticism of the 19th century).
I would like to reread Greenmantle and maybe a few of his other better known book.  Also his biography might be interesting - he seems to have led and interesting life.