I guess my angle is, how can someone shoot them selves in the foot with such power.
4) He is going to do some serious bird.
Will he? What law has he broken? I guess sex with a minor might be proved (well it's rape I think because under 16s can't give consent as far as my limited knowledge stretches), hard to prove, but what would constitute a long time in jail when you really look at the law?
We know there are many breaches of trust and professional responsibility, but what actually in law, I don't know. Anyone know about child law here?
Assuming the worst from the facts all these offences could apply:
Rape (it is illegal to have sex with a person under the age of 16.) I think there is some prosecutorial discretion where the defendant is also quite young (e.g. a 18 year old having sex with his 15 year old girlfriend) to charge them with a "lesser" offence, but I doubt very much that any court would see a situation where a man in his 30s had sex with a 15 year old pupil as a situation that calls for a "lesser" offence.
Abuse of a position of trust (if you are in a position of trust, e.g. teacher, the age of consent is 18 not 16, to protect vulnerable 16 and 17 year olds that might be unduly influenced by someone in authority). It's not just a question of professional ethics or morals, it is a criminal offence under the Sexual Offences Act.
Child abduction (removing a child from the lawful custody of the parents)
Kidnapping (you can't "consent" to kidnap if you are under 16, the same way you can't consent to sexual intercourse)