This morning there was proof that slugs and/or snails have been at my lettuce seedlings. In a try next to the lettuces were some coriander seedlings. This morning I found one with the leaves on the compost, detached from the stem, and a slight hint of a slimy trail across the top of the compost. I suspect one or two of the other seedlings might have disappeared, too.
So I’ve sown half a tray each of every lettuce variety I have once more. I suspect I may be playing “hunt the gastropod” for a few days to try to get rid of them.