There was a fault in my area last night. G31, now looking at the graph before the fault the chart is all over the place but after the service came back its been steady as a rock. You can see before the total fail of the service that the chart got a lot worse in respect to latency. Now its a lot lower and steady.
Not sure if they were doing a bit of work as the speed doubling was completed last week.
Although I do notice that everyone seems to have a similar blip around 8-10pm last night.