On that, at least, we might be able to agree, on Brexit.

A 'no deal' exit would likely result in a sudden decline in the value of sterling, which would mean that nothing would be cheaper, so what is the Brexit Party's answer to this? How would they keep prices down? Their policy, insofar as can be deduced, would be to unilaterally reduce tariffs to zero. Of course, under the WTO's most-favoured-nation rule, it would be illegal to discriminate on tariffs outside of a trade agreement. So, the UK would have to drop tariffs on chosen goods for the entire world. The consequence of this, obviously, would be catastrophe for agriculture and manufacturing on these islands, flooding the market with cheap goods and making Welsh produce uncompetitive overnight.