Was the grid having fun last night?

Our voltage normally fits within the 235 to 245 range 24/7 but last
night the UPS went into voltage trim modes several times, it does
this when the input gets above 250v. These were briefly just before
2100 and about 2215, from 0030 to 0230 and 0430 to 0530 (roughly).
The voltage plot from the UPS shows a couple of spikes above the
allowed upper limit of 253v.

Just wondering if it was a local problem (North Pennines, 33kV feed
comes from near Penrith) or more widespread.

--
Cheers
Dave.