Diesels on steam trips

I have reactivated this debate after seeing footage of Nunney Castle on its run yesterday (1/7) to Worcester when a DL was marshalled behind the locomotive and in front of the support coach.

I know that the Steam Dreams trip would have been full of people who just wanted a ride, a meal and a day out in Worcester but I suspect that those who just wanted a day out with Nunney Castle might have been bitterly disappointed. From the videos it seems as though this was more of a diesel hauled train with a bit of help from the Castle, presumably because of fire risk issues. Clearly the big railway would probably prefer all steam was oil fired, especially in the summer! (Ref: the oil fired debate in other thread)

I'm sure that it would have been a difficult 'call' for Steam Dreams and the Castle folk but the clue is in the name of this company and one day a legal expert may challenge the validity of such activities. This isn't a swipe at SD or anyone else; it just illustrates how complicated things now are in dry weather...and with particular locomotives, maybe? For example, last week Tornado blasted over the dry highlands of Shap and Ais Gill with no diesel in sight.

Perhaps, when a trip is booked, it is now time to be clear whether a DL will be involved, for operational reasons/convenience, as a requirement due to the time of year, or even because of the locomotive that it is planned to use. Do some engines pose more of a risk of a diesel than others? Then at least fare paying passengers will know what they are paying for and they can respond accordingly if they are looking more for a steam hauled trip than a version of one.