It's relatively rare for a train to become completely disabled mid-section and require assistance - even more so for a passenger train. I couldn't put a more precise figure on it,That's true, at least the Thunderbird could get around to the other end even if it did take an hour to do so.
Anyone have any idea how often this happens? I guess striking an animal is quite common but for that to disable the train?
I'm afraid!
Regarding the ability of the modern railway to respond, as raised by Taunton - I'd suggest that it's more efficient but less flexible nowadays. Yes, it'd be wonderful to have spare locos and crews everywhere - but, as always, who pays?