They might be better off trying to get reciprocal retirement rights in exchange for EU youth mobility. That could be sold as an actual win, and plenty of red wall voters would quite like the chance to be able to retire to Spain again. It would appeal to A Place in the Sun viewers etc.

The whole basis of a reciprocal approach designed to simplify access yet without crossing the actual CU/FOM/SM red lines is finding means through which Labour can keep some of its core support happy without looking as if it is walking back on campaign promises