A friend is getting herself all worked up as she passed through the UK over a week ago (a couple of hours transiting ar Heathrow) and has received a Trace & Trace message this evening telling her she's to isolate. We do not live in the UK and she has had negative tests locally since her return but she is wondering how the NHS can have her contacts? Is there some way the NHS can put an App on your phone without you knowing? She doesn't know anyone in the UK and certainly didn't see anyone she knows at the airport so it can't be that her contacts were given out! Any ideas?