Thunder Bolt
Silly old bat
It was a very different world. People bought most of the goods from local shops, which tended to have local suppliers. People ate seasonal food - the idea that we'd have strawberries in December would have been alien to most of us.
As we were pretty self-sufficient in food, had our own fishing fleets and a plentiful supply of coal, we needed to import far less. We now produce about 60% of our own food, so that alone adds to pressure on the ports.
On top of that, we had a big light engineering section, based mainly in the West Midlands, a thriving textile industry in the north and many motor manufacturers, again reducing the need to import. The car industry would have bought pretty much all its parts locally, for example - it's very different now.
You also have to consider that we had many more docks about 50 years ago - London docks handled about 40 percent of the UK's trade at one point - that's all gone (my father-in-law is an ex-docker and will tell many tales about the heyday of London's docks). Other docks have gone or have been scaled down so the traffic we have coming through ports now is concentrated on a few pinch points.
And don't forget, before we joined the EEC, we were a member of EFTA, so we already had a free trade agreement in place with many European countries as well as trade agreements with the Commonwealth.
You can't really turn the clock back to what it was like then, it was a very different world.
In a nutshell. It's not just food. The vast majority of insulin (90%) we use, comes from Denmark.
The government could have used the last 33 months sorting out trade deals so the exit could be as smooth as a messed up exit could be, but so many ministers have resigned without sorting out anything, it has come to panic, last minute, measures, which may, or may not work.