There’s some suggestion in records that this slate acts in the same way it would at the traditional ground level for the control of rising damp. I’m unsure if moisture would be present long enough for this to work in the same manner from a pitched surface. Also, the first mention of DPC we see in c.1840s becoming writ in 1875, our building is much earlier. The slates could have been added later of course.
This detail is often found in coastal regions, Scotland in particular. I can’t say how effective against wind driven rain or if there’s evidence comparing a building without them, but the technology is arguably noteworthy as it will have contributed to the method in which we design and protect joints in buildings today. At the very least, the feature is quaint and “adds a bit of charm”.
Back to the low bit. Sadness and colonialism I think may as well be a synonym, as we have many examples in time to pick from but feel this one is up there in human behaviours toward our fellow man.