I initially assumed they were pygmy hedgehogs but two signs clearly label them as Erinaceus amurensis. Size didn't strike me as abnormal for a four-toed hedgehog.
EDIT: Size was not abnormal for Amur hedgehogs either though
There were hedgehogs displayed in two tanks on my visit in Jan this year. One tank was labelled as containing "Hedgehog Erinaceus europaeus", while the other had two signs, one for "Common Hedgehog Erinaceus albiventris" and the other for "Albino Hedgehog Erinaceus amurensis".
My (very bad) photos of the animals are below - one of each tank.
