Comment by rdm_blackhole

The UK border agents (technically counter terrorism) can also stop you at the border, force you into a room, ask for your passwords to all your devices and you don't have the right to refuse.

You also don't have the right to a lawyer to be in a room with you and you are compelled to answer all their questions and they do not need to tell you why they stopped you.

Then if you are lucky they return your devices 7 days later after they have been through everything.

This guy went through it last year and talks bout what happens when they stop you: https://youtu.be/991kRp8KUmo?si=-5S1uLE7K9KG_gNj