I switched the PC off at 23.20 last night, and I thought up until that point
there were no spherics showing.
Having looked at my last UK map generated at 23.15hrs, there was indeed one
spot of spherics over Torbay.
Presumably this is where it all started - and looks as though it tracked
something like 060 degs across England.
That cell seems to have raced off towards Denmark, but there are new cells
forming now over the Scottish Borders.

Phil