Nick Clegg has been doing the rounds insisting that a hard or clean Brexit will lead to a rise in British food prices.

Nick Clegg is wrong, entirely so. The claim is:

He said: "A hard Brexit will lead us off a cliff edge towards higher food prices, with a triple whammy of punishing tariffs, customs checks and workforce shortages.

"We must hold Theresa May's Government to account and fight to ensure what comes next is best for British consumers and businesses.”

The claim that food exports could face higher tariffs is at least potentially true. But that would of course mean that British food prices would decline. For some of what is now exported would remain available for consumption domestically.

However, their real claim, from the full report, is this:

In the case of such a “hard Brexit” the UK will be obliged to impose tariffs on imports, while the EU and the rest of the world will be obliged to impose tariffs on our exports.

This is simply not true. To check our understanding we bothered to call a source in Geneva, something that perhaps Clegg and the Lib Dems should have done.

The claim is that a clean Brexit will mean that we must revert to WTO rules. Just for the avoidance of doubt yes, Britain is a member of the WTO in its own right, so definitely and definitively WTO rules would apply.

Those WTO rules say that there are ceilings to the tariffs which can be applied to imports from other WTO members. All British exports could and would face duties up to but possibly below those ceilings. Clegg is claiming that Britain would thus have to impose equal tariffs to imports into Britain. This is nonsense. We cannot apply higher tariffs than those ceilings, but we can apply any rate that we wish below them. Yes, we did check, 0% is an allowable rate below those ceilings.

Further, all that Most Favoured Nation means is that whatever rate we do decide to apply must be applied equally to products sourced from whatever WTO member nation. We can have a special low rate for camembert if we wish - as long as camembert from France gets charged the same rate as that from New Zealand then we're obeying the law.

The central contention here is therefore wrong. WTO and MFN rules allow us to increase tariffs up to the agreed ceilings on imports into Britain on the understanding that whatever rate chosen applies to all sources.

WTO and MFN rules do not insist that tariffs must be imposed upon imports. We are entirely at liberty to impose any rate we wish below those ceilings, including offering tariff rates of 0%. Which, given that we import some 40% of our food seems like a sensible idea. Why would we be so damn stupid as to make our own food more expensive for ourselves through our own actions?

Nick Clegg was once Deputy Prime Minister wasn't he? How well we must have been ruled back then.