After the completion of the UK withdrawal from the EU movement of migrants through the English Channel have continued, and possibly intensified.This article investigates the existing bilateral and multilateral legal framework applicable to persons wanting to reach the UK by sea as well as the constraints posed by these international rules to any unilateral action proposed or implemented by the UK with a view to taking back control of its southern shores. It is maintained that, after Brexit, the UK cannot any longer avail itself of the EU regime concerning movement of asylum seekers and migrants, thus diminishing the possibility of claiming coopera- tion from France (or any other EU Member State) to limit Channel crossings by such persons.