It doesn't happen so often now, but amazed at number of times ordinary pax have joined a steam special!
Remember particular incident at Derby in 1990s when various pax took some (considerable) persuading (stewards, multiple multiple pa annoucements, people on the special showing their tickets and reservations) that the special was not the regular service train they were waiting for, despite whatever the departure board was saying.
Maybe going off topic, but in some cases specials are still not shown on departure boards at all, or if they are they appear as if they were a 'normal' service.
Mind you, departure boards can cause confusion. In Sep joined train for Bristol and Taunton at Newport. Manchester train delayed 5 mins and was behind, not in front of, the mini hst. Quite a few pax got on assuming we were the Manchester train, delay at Severn Tunnel while conductor worked out what to advise them to do.