That looks like an awful lot of water there. Are they drowning?

I think you are OK. Those aren't the true leaves. Ease up on the watering. Keep the soil moist and don't let them sit in water. Looks like you have nice dark medium which is good.

Thank you both! They only get a light watering in the evening, but didn’t get any last night. However I will take that on board. Yes, it is the first leaves which are yellowing.

Just had a thought - have you had a cold night since you planted them? If so it could well be that. But as the new leaves look fine they should be OK. Re watering, one thorough watering that wets the soil lower down than just the surface is better than lots of light ones.

I hadn’t thought of frost damage, but I think you’re right. It’s happened to my neighbour’s too. Many thanks.

We hit 80°F today in NY - preceded by a big nasty storm. I don't think you'll have to worry about a frost.

New York is very long way from Scotland though! We do get some of your weather, modified by the Atlantic, after about five days but we didn't get your snow, though we did have a very cold wind a couple of days ago..
Canalhopper, it doesn't have to be actual frost to do that damage - a cold wind would do it. It doesn't appear to have damaged the true leaves though - hope they are growing nicely now.

Thanks Steragram.
Yes, they seem to have recovered now. I know that seedlings always have a pair of leaves which aren’t true leaves, but I hadn’t realised beans have them too! I thought it was just small plants like beetroot that have them.
Today I shall plant the rest of my runner beans, as the weather seems about to buck up.