That 30-40% of its population that has post-Imperial delusions need a rude awakening of what the 21st century world is like.
Then, the UK may rejoin the EU in 10-15 years time.
If they don't, they'll never stop believing in their Tooth Fairy and will hold the country to ransom for decades.
That can only happen going through the barren land of a no deal #Brexit. Sadly.
Yet, that doesn't undo "time". The referendum happened. It produced a result few people expected. You can't undo that.
Hari Seldon has the opportunity to shorten that period to 1,000 years only by establishing the two Foundations.