HRA Guidance simply states: "ROGS sets no minimum or maximum age for staff engage on safety critical work. However, the following are nationally recognised norms and it recommended that they are followed. No person (other than a trainee) ............should undertake safety critical work until they attain the age of 18. No person may perform the duty of driver of a railway train (other than as a trainee) under the age of 21. Staff may train for safety critical tasks once they are 16 (18 for drivers) They must not be allowed to undertake such work unless properly supervised by a fully competent qualified person. There is no upper age limit for staff undertaking safety critical work. To bar an individual from safety critical work on grounds of age alone may be a contravention of the Equality Act 2010." This Guidance is endorsed by the ORR. Interestingly, the Train Driving Licences and Certificates Regulations 2010 gives a minimum age for drivers of 20. There is seemingly some variation amongst heritage railways on age, which is why I'm interested. I hadn't realised that upper age limits were still enforced, though.