The Royal Scotsman failed at Markinch yesterday (Sat. 21/09/13). It caused chaos as due to the Stirling blockade all the Glasgow - Perth traffic was routed through Fife. Ouch!! 
If it had to happen, glad is was a diesel and so not a cause for more bad press for steam.
I saw this passing Inverkeithing (what a truly dismal town that is BTW) yesterday, about 10 mins before it all went wrong. Sounded fine passing through so I'm not sure what went wrong between there and Markinch. We had a clean run around the loop however directly behind it so it must have been somewhere between Thornton North Jn and Markinch that everything failed.
Does anybody have any more information on what actually happened?