Customer Ambassador: stands on the platform / concourse, a visible presence to assist passengers with relevant information, non-safety critical role, MS grade with a decent salary (varies with location) but no OT.
Service Delivery Assistant: (Train Dispatcher). Safety Critical role - Primary job is out on the platform and the safe, prompt dispatch of train services.
Station grade with OT (I think somewhere like Reading they are somewhere in the region of £24K basic)