Flat-Cap Driver refers to men of a certain age, 65+ out in their cars, usually on a Sunday afternoon but can be anytime really, who drive far slower than the road allows
Driving down the Motorway Maz and Giz encounter a slow car:

Maz (speaking out load to self): Hmm, come on it's not even Sunday, you're on a Motorway pick up some speed, you'll cause an accident driving this slow!!

Giz: Well what do you expect? Look you can see the driver, he's a flat-cap Driver, just overtake - can I poke my tongue out at him as we pass by?
by maz&giz March 8, 2010
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