Here come the 123s

I spotted this milestone this morning on the side of the road during today's commute to work, and snapped it (badly) on the way home. I've done it so many times but this was the first time I've seen it. Stow, Bath and Cirencester have all been in existence since Roman times (as has the road in some form - the Fosse Way) but I don't know how long that milepost has been there. If this was how people found their way to places in the past, it's a wonder anyone ever got anywhere!