A lot has happened to trade and commerce in the last 40 years, though. The volume of goods, services and migration across (internal) European borders has increased to a previously unimagined extent. Therefore the process of leaving the EU at this point is a lot more complicated than it was 40 years ago.We have been in the EU for 40 years ... that is not a very long time ... before the EU was formed they bought from us, we bought from them ... we visited them ('going abroad'), they visited us ... I cannot see that changing.
Now the paperwork for doing business is going to change but business (money generating) will carry on ...