The Age of Consent determines our cultural & personal attitudes to childhood, and what is appropriate in terms of adult / child relationships. In the UK that age is 16, no matter what it was historically, or what it might be elsewhere. There are very good reasons for this. Even so, it would be considered decidedly dodgy if a 16-year-old would be to become involved with a much older person. An age gap of even five years might be considered too much - it certainly was when I was 16 - though there are no legal guidelines & each case will be treated differently. Maybe we're straying into Rough Band territory here; each community will have its own commonlaw limits as to what is, or is not, acceptable - or what constitutes a loving mutual relationship or one of abuse, no matter how willing the younger party may think they are.