The UK is one of the 5 Permanent Representatives at the UN Security Council and legally cannot be replaced as a permanent member of that body without its consent.
There has been speculation about how and whether the UK's position at the UN Security Council would be affected by Brexit and the well-known Think-Tank, Chatham House, has published an Article on this subject in the November 2019 edition of its "International Affairs" journal. The article is co-authored by Jess Gifkins, Samuel Jarvis and Jason Ralph and is entitled "Brexit and the UN Security Council: declining British influence?"
The Article focused on interviews with 29 unnamed people, mainly based in London or New York, "with direct professional experience" of the way the UN works and also on two case studies "Somalia" and "Yemen", where the UK has in recent times been influential in helping shape the UN's own agenda for those conflict jurisdictions.
There has been much speculation that the UK position and influence on the UN Security Council and in other international bodies would be much diminished by Brexit but the counter-argument is that the UK stood to be replaced and diminished anyway by the rise of the EU as a body purporting to represent all the EU's members. The Chatham House Article does not really resolve the debate on these issues but concludes that , as the UK's material influence is diminishing anyway, its strength may, nevertheless, endure through the soft power that it wields through "its reputation for competence and [ through the fact that] its governance role in the Council enable[s] it to have a far more significant influence than its material capabilities would initially indicate".
The UK has a reputation for being a strong and effective "penholder" on the Council - "penholding" being described as a process whereby "a state takes political ownership for leading drafts of resolutions on a specific topic". It is argued by some that the UK's diplomatic skills in that context and in the international process generally will sustain the UK's importance at the UN Security Council level, notwithstanding Brexit. Another factor is the relatively high level of resource - currently, 0.7per cent of its gross national income - that the UK commits to international development aid and which increases the UK's importance on the world stage.
If there is any conclusion to be drawn from the Chatham House Article, it is perhaps that the UK's role in the UN Security Council will be affected by the future role of the EU on the world stage. The more influential the role of the EU, the less reason perhaps there is to argue for a separate role of the UK as a permanent member of the UN Security Council - and vice versa.
Let us see what happens!