It's legal unless he's in a position of authority or care. However, try this idea out for size, imagine he's finished uni and then done a PGCE (teacher training). Then he starts a relationship with a 16 year old who's still at school, though not where he works, so it's still legal... but it starts to seem pretty weird, don't you think? I have a 17 year old and she's very impressionable and vulnerable. Someone with a degree and a job is very much able to take advantage of her. There's no question that she could have friends that age- I did when I was young. As time's gone by, those who encouraged me to try out the same things they were doing turned out to be weird, and those who behaved like older brothers or sisters turned out well. Like many of the people replying above, I'd be suspicious of the older person. Those who consider this a conservative view might not share the values we have, that men and women should be equal- in some cultures different dynamics are acceptable, and people may be comfortable with a large power imbalance, which in Britain is generally not seen as a healthy relationship between equals. I'd advise your friend (and this is coming from a mature student) to have a really long think about what kind of relationship would feel good, feel right, and ask herself whether she's with him because she's flattered, and what it says about him that he considers a schoolgirl to be his type.