A brief search also reveals that this is not the first time the old girl has caused that in different locations. Would I be right in thinking that an inspection of the OHLE would be forthcoming, not to mention checking if the coal in the tender has been set alight?!
Too much coal in the tender https://www.railforums.co.uk/threads/6233-duchess-of-sutherland-ohle-arc-incident.225461/
One solution would be to have a telescopic cover over the tender and insisting all running is done with it closed. This would also protect from incidents of high stacked coal flying off for other reasons. The other would be better training of crew so they don't start until the coal pile has been brought within gauge.
Fascinating stuff. It's great that we can easily compare aerial photos of the present day to maps of previous decades. All without having to visit a library.