The following thoughts may help a little?
I was involved in exploring underwater sections of this hydrological system, at Leck Beck Head and Witches Cave. These are the main resurgences for the water which caused your problem. The water has to pass through a number of highly unstable chokes on its way out to daylight. We've had the opportunity to look closely at these chokes on many occasions over the years and, after every flood, when you go back the terrain has usually changed beyond all recognition. These chokes have cause desperate problems for cave divers and we have never really been able to sort them out.
It's obvious that the degree of restriction to flow in these problem chokes varies considerably. It's possible that one or more of these areas has collapsed following the last but one flood, resulting in a far smaller opening for the water to pass through than normal. If the Lancaster main drain is in spate - but the water can't get out as easily as normal, it's actually quite easy to see why the sump surface in Lancaster would rise extremely fast.
What can we learn from this? I think it shows that, even in a familiar cave system, we should expect the unexpected - despite the forecast. A cave is a natural feature and when nature is in angry mood we all need to be extremely careful. Are we in danger of becoming a bit too reliant on the results of fancy computer number crunching at the expense of using experience and considered judgement?
Having said that, the weather system which gave us that Atlantic storm at the weekend was accurately predicted several days ahead of when it happened and such weather systems can often be very severe. So I'm not convinced that the signs of a possible major flood weren't all there in advance.
Please can I stress though than none of the above is criticism of anybody. Even I wasn't aware it rose that fast in Lancaster, despite being very familiar with the submerged route between there and the risings.