Back to first principles. Trade deals take years because they commit policies across a whole range of complex areas where policy making takes time. Deciding all such policies in a few months in order to commit it in treaty with your main trading partner is not good government.

Among the policies we need to decide in the coming weeks for trade deals - state aid, public procurement, animal welfare, food safety, environmental protection, labour, agriculture imports, immigration / work visas, goods regulations, standards, conformity assessment...

But we just want a simple trade agreement with zero tariffs...? In the 19th century perhaps. In the 21st century trade partners want to make sure those tariff cuts are meaningful, and that means ensuring competition is fair both ways.

I forgot a few. I don't know what our policy is on data protection and data flows, access to our financial and insurance markets, investor protection, recognition of qualifications obtained elsewhere...

Oh and that's quite a lot of diverse interests and stakeholders you need to be keeping happy. Many of your own MPs will have some keen interests in their constituencies. Some major employer who may leave if the deal isn't right in some way.

And haven't we already seen in the last few weeks what happens in the battle between the UK government's simplified view of the world and reality? Trade deals in weeks, like the contact tracing app etc etc. /end