pre-commit hook compliance iteration (some automated, some manual)

[seefood]

bringing the code to compliance following #871

[philclifford]

Thanks, that's useful and informative. Before spending effort resolving these new conflicts maybe wait a while in case #871 receives change requests and/or #856 progresses. Some of these fixes are also present there and testing both #871 and #856 requires some extra care and thought.

Also I see the automated testing is having a think: I suspect at least that will be trivial.