Visitors may not know this, but maybe they should.
Officers use counter-terrorism laws to remove a mobile phone from any passenger they wish coming through UK air, sea and international rail ports and then scour their data.
The blanket power is so broad they do not even have to show reasonable suspicion for seizing the device and can retain the information for “as long as is necessary”.
Data can include call history, contact books, photos and who the person is texting or emailing, although not the contents of messages.
David Anderson QC, the independent reviewer of terrorism laws, is expected to raise concerns over the power in his annual report this week.
He will call for proper checks and balances to ensure it is not being abused.