Personally, I would enter the thread title as du Maurier, George: blah blah blah
disclaimer: This is my personal preference, I don't know if it is good advice or not...
I would prefer this because that will affect where the name will appear in the Ebook Index (the master book list), and I do believe people would search for Du Maurier rather than for Maurier. Well, anyway, folks who have a similar mindset to my own.
Am I the only one who uses the Ebook Index to search for titles or authors?