Olympian/former world champion Mark Jamieson admits to child sex charges

but the teenage years do throw up a huge grey area,

Absolutely. This is why I generally favour the status quo. We have a fairly broad legislation with, as mentioned upthread, a range of judicial lattitude. A judge can apply a tailored degree of sensitivity to the case as set before them. I'd far rather a sliding scale placed at the judicial end of the law rather than the prosecutive. In the latter it has often proved to be inadequate and disasterous.