There was also a Roman fort/travelling camp near Enville Common (crop marks only these days).
I think the British Midlands must have taken the same fate as the Irish midlands. Too wooded for much of the time and coastal and river sites were favoured. This is probably because of ease of reach and good marginal resources.
It is hard to imagine, but as late as the 15th Century Sherwood Forrest was huge! If you find an old map of it you'll be amazed!