You definitely shouldn't have cut back on the water. One foot high for runner beans is still pretty much a "seedling". Sounds like your plants are stunted from lack of water/nutrients. I'd definitely start back up on watering them asap.

What sort of soil are they in?

Thanks. They are in compost amended Carolina clay soil. Amazingly it is the only part of my yard I found earthworms in. I do have a bit of erosion just in front of them on a hill though so I think it doesn't retain water very well at all. I'll have to be more careful to water more often then. Unfortunately I tend to neglect my backyard more then the front. I'll have to change that though.

You might find as the weather warms up they will slow down on the growth -mine seem to stop altogether then when it cools down again they will start growing like gangbusters again --the bean are yummy too --grew up on em .........
Janice the Brit

I am also a Brit and grew up on runner beans, not only are they delicious but the flowers are so pretty too. They do seem to prefer cooler weather-
Hi Janice, nice to know another Brit on this side of the pond!
Jenny