As I recall, this guidance came about after an AAIB recommendation where an aircraft with severe problems (perhaps only evident after the flight was completed) was vectored over central London.
Yes, if you're referring to the Evergreen B741 event, the full extent of the aircraft's incapacity wasn't initially known (to ATC):
ATC’s intention was to use 35 track miles from when the aircraft was heading 315º to radar vector it from the left base position onto the final approach. At that stage the controllers believed that the aircraft was capable of reduced thrust and not suffering a total loss of thrust on the three remaining engines. It was only when the co-pilot transmitted the warning that there may not be enough power to make the landing did the full extent of the problem become known.