Wall Mile 16 [HB 173]
Approaching the crest of the hill, the narrow pavement turns into an equally narrow piece of worn verge, before we encounter a short diversion through the edge of some woodland. This is usually boggy and beset with the plastic reinforcement mats with which we shall become familiar in various soggy places on our journey.
We descend steadily, the large strength-sapping stone ballast next to the reservoir soon making heavy going (it is easier if you walk on the grass to either side, where possible). We are on the line of the ditch and there is indeed a slight depression, but little by way of detail to be seen. Ahead of us, the reservoirs are spectacular, even though they are a modern addition to this historic landscape.
When Duncan Campbell and Hugh Debbeig (two engineers and map-makers attached to William Roy’s Military Survey of Scotland) were conducting the survey for the Military Road in 1749, they found time to note a portion of curtain wall standing along here, west of Harlow Hill, to a height of four courses. This of course was soon converted into the raw materials necessary for road construction, but the degree of their antiquarian interest is intriguing. One cannot but wonder at how broadly they interpreted their brief to survey a course for a new road so that it included mapping large parts of the Roman Wall as it then was. Indeed, their detailed survey seems to have been a major (and perhaps the only) source for the map drawn up by Nathaniel Hill for John Warburton’s rehash of the section of Horsley’s Britannia Romana that dealt with the Wall. And they tell us piracy is a modern problem in the publishing industry.
The Trail leads us downhill, past the lower northern reservoir, towards a crossing of a side road (the usual caution is advised). Nobody will be surprised to learn that the reservoirs have obliterated all trace of the Wall, even the Vallum, here.
On the far side of the road, and still on the line of the ditch, we begin our climb up to the site of Milecastle 17.
Milecastle 17 (Welton) [HB 173; haiku]
This was a short-axis milecastle, excavated in 1931 and 1999, its northern part lying beneath the modern road. Its main distinction is to have a radio comedy set in it.