I've ended up reverting the entire changeset. JOSM didn't make it easy for me to select and revert just the buildings on Margaret buildings. So I've just removed it. I'll reapply edits to Brock Street separately another time.

That said, I'm still not 100% sure why the buildings are better this way. The satellite imagery is pretty clear on where their left edge is in both JOSM and ID.

OK, I'll revert these changes. Leave it with me.

Actually I see that JOSM has a revert plugin, would you prefer it if I reverted the whole thing then reapplied changes to Brock Street?

Let me know what you think is best.

For example, should I redraw with Thunderforest landscape background. I can see there's a difference there now that I look. Same with the OS Open Street View, although that doesn't have hard edges.

Hi Dave,

Happy to edit to fix up the Margaret's Buildings buildings, though want to keep Brock Street as that's now correct. So will edit the buildings separately rather than try and revert this whole changetset (which I'm not sure how to do).

I'm not clear on what you mean by map the extent of the roof though. I was using the Bing imagery and thought I was following the roof outlines. Do you have a better alternative?