You're misunderstanding how it went. The 5% that's mentioned as the Low Frequency Demand Disconnection scheme, who were disconnected in managing the incident, i

You're misunderstanding how it went. The 5% that's mentioned as the Low Frequency Demand Disconnection scheme, who were disconnected in managing the incident, is a scheme where very high volume users (those who have a meter reading taken every hour) voluntarily opt to have interruptible supply for better prices. When the grid needs to, they're given a power cut that they signed up for. Commonly used by big manufacturers, smelters etc. It's in their contract, expected and gets them lower electricity bills. It helps prevent the grid tipping into catastrophic shutdown when there's no backup generation left, or something major has tripped, as part of demand management. If it hadn't happened the consequences would have far more headline-worthy. Railways, hospitals and the like that encountered issues were part of "the rest". That is not part of the 5% turned off, but the small part of the 95% "rest" that can't cope with some (larger than usual) drop of frequency. If they're buying trains that can't cope with a frequency slump or backup systems that aren't tested that's outwith grid control. That's a sign their systems need to be improved, and tested properly too.