A similar thing happened here in Australia (New South Wales) in the mid 80s. I was part of a rail preservation group and we were taking a stream locomotive with an empty train from West Ryde Station to Central, from were we were going to depart for an enthusiast's trip. One of the suburban trains was cancelled, so Jock, the station master, asked if we would like to run the regular suburban service, which we did. It was great fun pulling in and watching the passengers do a double take as their regular train turned out to be a steam train.