Andrew Adonis has just made the case for Britain to declare unilateral free trade

This is not what Andrew Adonis thinks he is saying but it is the meaning of what he says. His basic case is that we simply cannot renegotiate all of the varied trade agreements in time therefore we must stay in the Single Market and the customs union:

Setting aside its merits, there is a huge practical problem with hard Brexit. Leaving the customs union and the single market requires the UK by March 2019 to negotiate new trade treaties not only with the EU27, but with the 75 other nations with which the EU has free or preferential trade agreements, if British trade is not to take an immediate and substantial hit. Between them, these 102 countries include most of the trading world, and account for more than 60% of UK exports of goods and services.

As it is impossible to do all that negotiating therefore we must stay.

One possible solution is that we are indeed part of all of those trade treaties already. We conform to them all etc, so why not take a copy, scratch out "EU", write in "UK" and sign it? Sure, we know, treaties don't work that way but why don't they? 

There is also the more logical method, our preferred one. Free trade treaties are not in fact free trade treaties, they're nothing of the kind in fact. Rather, they are the details of the remaining restrictions upon trade. The difficulty in negotiating them is in working out which restrictions should stay. An easy method of dealing with that problem is thus to have no remaining restrictions. The draft post-Brexit trade treaty for the UK is thus as we suggested a couple of days ago:

1.There will be no tariff or non-tariff barriers on imports into the UK.

2.Imports will be regulated in exactly the same manner as domestic production.

3.You can do what you like.

4.Err, that’s it.

We do think it will be pretty easy to get everyone else to sign up to that. It would also mean that we would have adopted the only rational stance anyone can have with respect to trade: unilateral free trade.

As we did in 1846, and which is entirely not by coincidence when the Engels Pause ceased and real wages began rising substantially. Because it is the imports part of trade which makes us richer and so why should we try to place limitations on how Johnny Foreigner can make us richer?