The meaning of "major incident"
Interesting data, but I don't find these raw figures very helpful on their own. As the correspondent noted, there's no mention of the duration of the incident. Also, I don't get any sense of the severity of the impact as there's no detail about which bank functions were affected. Some of the things that banks do are more critical or time-sensitive than others.
As an example, the inability to process outgoing debit card payments for even a couple of minutes could be extremely inconvenient (not to mention embarrassing) for the customer. By contrast, if the system that handles my outgoing standing orders is down for (say) 20 hours but eventually manages to send out a payment slightly late on the same day it was already scheduled to be paid then I probably won't even notice that. The first outage is a real nuisance, the second far less so - although still serious from the bank's perspective, of course.
I was curious as to what "major incident" means so I went digging... The relevant regulation appears to be http://www.legislation.gov.uk/uksi/2017/752/regulation/99/made - it doesn't classify incidents, although regulation 98 says "... the payment service provider must establish and maintain effective incident management procedures, including for the detection and classification of major operational and security incidents". I interpret this to mean that each payment provider can have its own definition of "major incident". In which case comparing the numbers between different banks won't necessarily yield an apples-to-apples comparison. A more honest bank (if such a thing exists!) would look worse than its competitors, so without strong oversight of the criteria used, the likely effect of this kind of publicity is a race to the bottom to define "major incident" as narrowly as possible, thereby defeating the purpose of the regulations in highlighting such problems.
It's a pity because in principle I welcome greater transparency in this area, just not sure it will work as intended.