The substantial delays to services between Salisbury and Westbury were down to a large lineside fire at Upton Scudamore, between Warminster and Dilton Marsh. Unfortunately the details do point to the steamer as being the likely culprit; the fire affected a large area of the bank immediately alongside the line, largely inside the boundary fence, in a rather remote and isolated area away from any other obvious causes. The geography of it was causing the fire brigade considerable difficulty in reaching and tackling it, and it was reported to be 150 metres across at one point.
It could have been somebody on the bank I suppose, not sure what the official outcome is so far. Either way I'd think there's little doubt that the finger will point squarely at the excursion whether it was the loco or the railfans gathering lineside which caused it.
Sadly not a glorious day for the railtouring fraternity :cry: