South Africa has an interest in ensuring that Brexit doesn't cause much disruption in its major export markets, or to its main source of foreign direct investment. But a raft of questions arise that are difficult to answer.

By the end of January 2020, the UK should have passed the Withdrawal Agreement Bill into legislation, giving Prime Minister Boris Johnson's Conservative Party-led government full discretion to finalise a new trade deal with the European Union (EU) by the end of 2020. The Withdrawal Bill makes it "illegal" to extend talks beyond 2020.

There is a commonly held view that the Johnson government, which now has a solid parliamentary majority, is in a much better position to negotiate a good deal with Brussels. This view is wrong. While the decision to leave the EU is a political decision, the process of actually leaving and making the necessary arrangements subsequent to leaving is an economic and legal/technical question. A parliamentary (but not a popular), majority might allow Johnson's government discretion to strike a deal with the EU, but he will find that he can't negotiate with objective reality.

One objective reality is the UK's geographical location just off Europe. The gravity theory...