I personally knew the chap auditing SCADA in power distribution back in 2001, so I'm fairly confident the level of competence and what governmental bodies handle such issues.

But nothing is perfect, and whilst an edge case, space weather can and does wondrous things to pylons. It's planning for such outages and the layers of vulnerability in systems that such an event can expose in which you want top people on the case and planning around such exposures. After all, you don't want your fallback site all secure but nobody put the electric security doors on their own redundant power. Might end up with such doors opening automaticly and allowing anybody in, or not oipening and preventing access to the big red switch to failover onto some backup system. Things like that you just can't overlook.

But with power-grid distribution systems, their will always be a few weak points, case of if these three transformers suddenly went offline the cascade effect would be horrific. It's those cases you need to plan for. After all, 3 lorry accidents crashing into those transformers, whilst not very likely to happen at the same time - people win the lottery every week with much higher odds.

If that was the intention it backfired because it highlighted several problems to National Grid that they weren't aware of before.

There is some version of reality in which this was the point, if we are more charitable to the attackers motives

The 2015 attack on Ukraine power grid (https://www.wired.com/2016/03/inside-cunning-unprecedented-h...) may be relevant here.

It didn't sink itself though. There was no loss of the entire grid.