HarryT, you've seen text markup used in PG texts. There's no reason one cannot use a text editor and do text markup to denote various formatting that needs to be applied. Then all that needs to be used is a good text editor such as Notepad++. It's very easy to search/replace to put in all the <p></p> around every paragraph. Then load that into Sigil and go from there. The resulting eBook will be a lot neater codewise then it would be coming from Word. Also, there's no need to have to do the cleaning up you do with most Word documents.
For me, it is actually easier to format that marked up text file then it is to deal with a Word converted ePub. CSS is not that difficult to learn to format most eBooks as most eBooks do not need complex formatting.