The lines of these roads, if produced, strike the Thames not at London Bridge, but at the old "Horse Ferry" to Lambeth. This may point to an alternative (perhaps the very earliest) route.
Guest ('Origines Celticae') derives "Ermine" from A.S. eorm=fen, and "Watling" from the Welsh Gwyddel=Goidhel=Irish. The Ermine Street, however, nowhere touches the fenland; nor did any Gaelic population, so far as is known, abut upon the Watling Street, at any rate after the English Conquest. Verulam was sometimes called Watling-chester, probably as the first town on the road.
The distinction between "Street" and "Way" must not, however, be pressed, as is done by some writers. The Fosse Way is never called a Street, though its name [fossa] shows it to have been constructed as such; and the Icknield Way is frequently so called, though it was certainly a mere track—often a series of parallel tracks (e.g. at Kemble-in-the-Street in Oxfordshire)—as it mostly remains to this day.