New Wharf Pottery opened for business in 1878 then became Wood & Son in 1894. You can check these marks out online. Conway shows a knot with a crown on top, as does New Wharf. Marks can be confusing with many variations on a theme. Also, the mark of a particular company often changes over the years which is a great way to find the age of a piece.
You can find out how to identify Flow Blue by consulting books such as Mary Frank Gaston's "Collectors' Encyclopedia of Flow Blue China." If the mark on your plate does not ring true, it may be a reproduction. According to RubyLane, many repros show an unglazed bottom rim while authentic pieces are fully glazed. Some reproductions show a blue-green tinge instead of cobalt. Also, newer maker's marks are usually two to three inches wide, while original pieces are marked with smaller, one-inch marks.
You can find out more about Flow Blue marks as well as reproductions by joining the Flow Blue International Collectors' Club. They feature a Flow Blue Pattern Identification Project with over 1600s items.