Taken from the OFSI FAQ general guidance:
UK financial sanctions apply to all persons within the territory and territorial sea of the UK and to all UK persons, wherever they are in the world. This means that:
• All individuals and legal entities who are within or undertake activities within the UK’s territory must comply with UK financial sanctions that are in force.
• All UK nationals and legal entities established under UK law, including their branches, must also comply with UK financial sanctions that are in force irrespective of where their activities take place.
So that's all of us then..