FWIW I am in London too and have had several more than that, some for more than a few hours. There was one just the other day where the RAF museum in London was

FWIW I am in London too and have had several more than that, some for more than a few hours. There was one just the other day where the RAF museum in London was partially shut because the power was still out from the night before, much to my kids' annoyance. These have usually been down to a local substation going bang/being hit by a bus/curious-but-now-crispy-cat etc though, rather than the whole city going down. These sort of blackouts affect smaller areas, like 1000 houses at once or whatever, and not the entire city or region