Three snails

Three snails

Observation - Three snails - UK and Ireland. Description: I am fairly sure that the left-hand snail is a darker variant of Cepaea hortensis but I am wondering about the right-hand one; it also has a yellow central core to its shell but is otherwise morphologically quite different. I don’t know the name of the sm

I am fairly sure that the left-hand snail is a darker variant of Cepaea hortensis but I am wondering about the right-hand one; it also has a yellow central core to its shell but is otherwise morphologically quite different. I don’t know the name of the small snail and would be grateful for an ID