[DanBC]

You sometimes see a drystone wall that has a mortared top. Here's one example: https://www.google.co.uk/maps/@51.8862561,-2.0573352,3a,24.1...

Just down the road there's another, less attractive, example: https://www.google.co.uk/maps/@51.885003,-2.0568722,3a,46.6y...