No one's moved the wall; it's never been the border between England and Scotland. It marked the end of Roman territory; well, until they built the Antonine Wall (which is entirely in Scotland)
The
Antonine Wall, known to the Romans as
Vallum Antonini, was a
turf fortification on stone foundations, built by the
Romansacross what is now the
Central Belt of
Scotland, between the
Firth of Clyde and the
Firth of Forth. Built some twenty years after
Hadrian's Wall to the south, and intended to supersede it, while it was garrisoned it was the northernmost frontier barrier of the
Roman Empire. It spanned approximately 63 kilometres (39 miles) and was about 3 metres (10 feet) high and 5 metres (16 feet) wide.
Lidar scans have been carried out to establish the length of the wall and the Roman distance units used.
[2] Security was bolstered by a deep
ditch on the northern side. It is thought that there was a wooden
palisade on top of the turf. The barrier was the second of two "great walls" created by the Romans in Great Britain in the second century AD. Its ruins are less evident than those of the better-known and longer Hadrian's Wall to the south, primarily because the turf and wood wall has largely weathered away, unlike its stone-built southern predecessor.
My own theory of why they tried moving the wall a little more north was two lines of defense against my ancestors.
Once those Picts breached the second wall ‘‘twas not to be a pretty picture in the Roman villages, ya know.
”