This year, instead of bagging up the fallen leaves, I have spread them over the empty vegetable plots as mulch. One plot is just bare earth; the other two have a green manure sown in them. Will this mulch do any harm? And might it do any good?

Hi & welcome : ) Generally an excellent plan! What kind(s) of leaves?

Mainly cherry and greengage leaves

Those sounds great! Fine leaves to use as mulch.

They sound like small leaves that will compact and maybe allow some of the cover crop to grow through.
I'd monitor over winter, try to break up any clumps- some leaves get wet and make mats.
My concern is voles finding it too comfy and making a colony there. That generally does not happen for me, but this year I already do have voles in one area, so I am more concerned.

Thank you for your advice. I should have made it clear that the Cambridge I live in is in England, not the USA. Nonetheless, your advice, both of you, does sound good. We don't have voles here, but mice possibly and slugs and snails definitely.

Happy to reply. If you have worms, the leaves won't last long.