Define "Downpour".

Been hearing that Vine fellah outlining "what to expect from the coming downpour."
Many decades ago some of us were standing on one side of Lord mayor's walk" in York. 
One looked at t'others and said - "It's gonna."
T'others returning the look, said - "it's GONNA!"
All set off to run across the road.
En route ALL yelled, in unison "IT HAS!"
We were sodden before we got across the road - THAT's a downpour.

I've just donned a "Fleece" toddled out to the rain-gauge I only returned outdoors, clean and empty, four hours ago - SO - you're looking at four hours steady "downpourless" rain.
o.4" in four hours
Got back in after 3-4 photos, removed barely damp Fleece, shirt bone-dry.
I'm bound to wonder what 24hours PLUS a named storm heading this way will add?
If I flood Cumbria is under several 100 feet of water.