Most TOCs will have policies along the lines of needing to wear a name badge for customer facing roles (this may or may not include drivers, depending on your chosen point of view!

), and also a need to wear I.D. when in any non-public area, which is a Transec (Government body) requirement on which the railway is audited (allegedly).
In these days of social media etc, it is not appropriate for any member of staff to be expected to offer their surname, nor is there ever a need for anybody to be furnished with this, and as such most frontline staff will have a namebadge showing just a first name. Managers, in my experience, tend to have their full name on their badge, for whatever reason. The Transec I.D. can be a thorny issue if a TOC requires it to be worn all the time, which has happened in the past, as it means by default that a colleague's full name is on show.