It's possible:
* The name is slightly misspelled: You might be thinking of a different author with a similar name. Double check the spelling.
* The author is relatively unknown: It's possible the author is not well-known or has written in a niche genre.
* The author writes under a pseudonym: Some authors use pen names, and "Bertrand N O Walker" could be one.
To find the author, you can try:
* Searching online databases: Look for authors in online databases like WorldCat or Goodreads.
* Checking libraries and bookstores: Check the catalogs of your local library or bookstore.
* Asking a librarian or bookseller: They may be able to help you locate the author's works.
Please provide more information if you have it, such as a book title or a genre, and I can help you search more effectively.