Judith in England wrote:
I realise that once the beans become really established - there is much foliage
and I suspect little direct sunlight getting through them to the ground between
the rows.

You could do the whole 3 sisters thing - beans up sweetcorn with a
ground cover of courgettes. Although tbh, I tried it and it didn't
work so well. But courgettes and beans should* work /after/ the
beans are established (so the courgettes don't block their light)