The UK Minister for intellectual property recently stated that the UK will ratify and join the Hague Agreement for International Design registrations by March 31, 2018. The service will come into effect on April 6, 2018. As of now, UK-based applicants are able to apply for an International Design by virtue of being part of the EU. This separate ratification by the UK will ensure that UK-based applicants will continue to be able to file International Design registrations after the UK leaves the EU.
Under the Hague Agreement it is possible to submit a single ‘International’ design application which covers selected states that are members of the Hague Agreement. By virtue of the UK joining the Hague Agreement, the UK will also be individually selectable from April 2018 as a designated state rather than only via an EU designation.
Source: SMD Country Index- Boult Wade Tenant, United Kingdom