The Bentham line has a 2-hourly service for much of the day,
Ah - the caveat here is 'for much of the day', i suggest.
(It's a bit late, but I think this issue is worth looking at still.)
Let's look at the afternoon trains. There are departures from Leeds for Lancaster/Morecambe at
12.18, 14.18 (you got your two hours there ok) and, er ... 17.26.
So that's 3hrs and a wee bit. And that's a slot when a fair few will be travelling (relatively), as shown by the two departures for Carlisle - at 15.18 and 16.48 (and both usually four-car trains, I believe).
which is adequate for the displaced through passengers.
Depends on what one means by 'adequate'. I don't suppose anyone on the two Lancaster trains that afternoon died of heat stroke, but failing to plug a gap between 14.18 and 17.26 for passengers to Gargrave and beyond when you possibly have stock and crews standing idle because the line is blocked at Ribblehead doesn't sound adequate to me.
The block section from Settle Jn to Carnforth requires 40min which is a challenge too.
You can't fit two return workings in between (roughly, adding an hour on after dep Leeds) 15.18 and 18.26 from Settle Jcn to Carnforth? Some challenge, that!
Don't get me wrong. I think the people at Northern at all levels (despite the many complaints about other services) make a great effort to provide a decent-ish service on both the S&C and Bentham (and Tyne Valley) routes, given the financial and stock constraints, and passenger demands. This includes both strategic and day-to-day operations. (I think both routes probably have the best service levels ever with the current timetables.)
It's also possible that the crews stuck at the Leeds end of things were Carlisle-based, I suppose, and don't sign the Bentham route. Or there was one person only in charge of sorting out the passenger mess, and he or she concentrated on getting RRBs. I don't know, but it would be nice to have an explanation as to why no extras could not be conjured up for the Bentham line in the downtime.
BTW I wonder if the KWVR picked up extra traffic yesterday as a result - it was relatively busy. Ill wind etc
Remains unanswered.