97. Who devised the Wall Mile numbering system?

The philosopher and Wall scholar R. G. Collingwood began the scheme of numbering the milecastles from east to west, with MC1 some 1.15km (0.78 Roman miles) south-west of Wallsend fort (and thereby begging the question of whether there had been a MC0 south-east of the fort). Milecastles first gained their name in 1708, courtesy of Robert Smith, whilst turrets had to wait until 1726/7 for Alexander Gordon to coin the term.

Further reading: Birley 1961