The issue is that I get a lot of unwanted white space above and below facetted plots when using coord.fixed() (and with theme(aspect.ratio = 1)) but not with plots without the facetting.

First a simple plot: no unnecessary white space.

Now facet the plot without coord_fixed(), no unwanted white space.

And then this which adds facetting and illustrates the additional white space appearing when I add coord_fixed().

There was a suggestion on the web, but about a slightly different issue about scales = "free" in the facetting that using theme(aspect.ratio = 1) was better than coord_fixed(). That doesn’t change things for me.

Using theme(plot.margin = margin(t = 0, b = 0)) has no effect.

Using theme(plot.margin = margin(t = -70, b = -70)) also has no effect.

Set margin units explicitly with theme(plot.margin = unit(c(-5, 5, -5, 5), "cm")), still no joy on the vertical space though it can be seen that the right and left margins are imposed correctly.