Too many hard Brexiters know they have peddled false hope and oversold their case. The price of trading in the EU on World Trade Organization rules — the alternative to a deal on a new EU free-trade agreement — is giant, perhaps as high as £58bn, or £884 per person, according to analysis by the Institute for Fiscal Studies (see paragraph 152). We cannot have a border constructed on dogma — that would strangle our trade to death.

The hard Brexiters might feel it brings them moral purity. But their purity will mean our poverty. Today, the Trade Select Committee concludes that WTO rules will not permit tariff-free, frictionless trade and therefore the ‘no deal’ option should be discounted. This must not become the era of ‘Little England’ when it is time for Britain to pioneer new relationships. The prime minister has the perfect chance to take this step and join EFTA. The select committee’s report, with cross-party backing for the government to publish a white paper on EFTA membership before the summer, is a positive start.

Here's the argument in full at the Financial Times: https://www.ft.com/content/1a9e5444-0296-11e7-aa5b-6bb07f5c8e12