What is the author's style in The Eagle of the Ninth by Rosemary Sutcliff?

The author uses language effectively to evoke a sense of place and time in this historical novel. She uses the Latin place names for English and Scottish cities, including Aquae Sulis for Bath, Dubris for Dover and Caledonia for the Scottish highlands. The net effect of these terms is to create a sense of a complete, perfectly realized alternate world that bears only fleeting resemblance to anything the reader is familiar with.