I apologise for going AWOL, i posted this in work (while looking for the solution) and then went and took an extended weekend.
Anyway, you guys are incredible - Pilou, your method is perfect for a gentle column angle and Takesh h, your method of using the intersect curve from Round Corners.rb will prove perfect for more acute angles and Box, your advice about trying to take a component and re-use is well heeded. Your collective enthusiasm to help us mere mortals is inspiring.
I admit I was hoping for a quick fix plug-in (since I have about 25 unique geometry columns to model) but both your steps are very clear and reproducible so shouldn’t take too much time… as long as the scheme doesn’t keep changing like it did today 😕
Oh, and Rich O Brien, the Blender demo makes me wish we used something more advanced than SK in my office.
Cheers all!