According to John Redwood MP there are no treaty obligations for ANY exit fees and we should politely tell the EU commission where to stick them. Hopefully, where the sun don't shine.

The worst case scenario when we leave is no agreement and having to trade under WTO rules. These tariffs are generally in the order of 3.5 to 5% with the exception of agricultural produce which can be up to 40% and cars which are 9%.
Now these tariffs apply for imports and exports and we have a massive trade deficit with the EU in food and cars where we import much more than we export, so our taxes will get a boost as a result and EU goods will become more expensive. As the trade balance is in the EU's favour we can use the revenue we collect on their imports to subsidise our exports to the EU so our prices in Europe don't go up and pocket the difference.

This disadvantage is that our food goes up in price, except it won't if we conclude trade deals with food exporting countries like Australia, New Zealand, Canada, US, South America and Africa where our food prices from these countries are currently at EU support CAP and inefficient French farmers tariff rates of up to 40%, which will post-EU be set at whatever rate we agree in our bilateral trade agreements with these countries. So in reality expect our food prices to fall by at least 15% from their current ones.

I'm sure French farmers will quietly take it on the chin as they build up huge food mountains where they have never been known to protest or riot to protect their vested interests.

The reality is the EU commission will work as hard as possible to punish us for leaving as they can't lose their appointed jobs via the ballot box, the inverse applies to democratically elected governments in the member countries which is why several governments are behind the scenes already working on their negotiating postions for trade agreements with the UK, especially the Germans where we are their third biggest export market. When it comes to EU economics, Germany has since 2008 ALWAYS been in the driving seat and have forced through what they want. Bloody mindlessness, rising unemployment and being in a recession for at best in most of the EU marginally growing economies, due largely to the EU and Euro policies puts Europe in the weaker position. Having to face the ballot box under these conditions means imo the the EU countries governments will be pragmatic and will win this battle against the EU commission.

Junker will have to console himself by drinking the new EU wine lake dry, where we are buying our wine from the rest of the new world.

We are actually in the much stronger negotiating position, with much due imo to the EU bias against the UK in their single market in goods but only in a very limited way in our strength of services, so we have progressively had a worsening trade balance with them. Leaving the EU means this changes to being a negotiating strength.

Another potential boost with leaving the EU is that we can dump their crazy, industrially suicidal, when competing with most of the rest of the world, by dumping their tree hugger, plant food centric energy policies, so our industries have much cheaper energy prices. Like the US this will onshore much heavy industry we have lost due to our uneconomic energy cost compared to much of the globe.
