I've been thinking about this and you know something? I think Andrew is right, we're well up the creek and no paddles to hand.
We import crops from the EU because we don't know how to grow our own. We import meat because we can't rear livestock. Milk and Cheese are imported because we lack the technology to produce it Chickens? heck yeah, we have a country full of those.
Cars, well I guess most of those come from abroad too . . along with TV's, Mobiles, Microwaves and Dishwashers.
Clothes, Carpets, Furniture, all mass produced and shipped in daily.
Service industries . . . well that's just a few computers in an office somewhere, could be anywhere in the world (that's cheap enough).
Banking? see above.
Gas & Electricity comes from . . . oh yeah.
So, after mulling over this little puzzle I realised the only thing we have in this country to generate cash for the economy is . . . speeding fines