No. It's not. The law is that you have committed a crime if you have sex with someone aged 13-15 when you either know they're underage or when it wasn't reasonable to believe they were over 16. You have also committed a crime if you have sex with someone aged under 13 regardless how old you think they are. In the latter case, the law also makes provision for a judge to go outside the normal sentencing range in a case deemed to be highly unusual, which is what the judge did.
Yes it is. As I said, if a teenager over 18 makes a 'reasonable assessment' that their partner is over 16 but they're not sure, if they are wrong they are open to a charge of sexual activity with a child. That's just a fact.
If it came to it, they would have to convince the police and the court that belief was reasonable. And they might fail.
As we all know there are blokes who don't ask, don't care or actively target a girl who is underage.
The standard defence for being caught having sex with an underage partner is reasonable belief that they were 16, everyone uses that. Doesn't mean they believed it, or the belief was reasonable or that they even asked.
Equally, the standard defence for rape (of complainant 13 and above) is reasonable belief in consent. Everyone uses that too. In that case you also have to show that that belief was reasonable. Ultimately it's up to the court to decide.
Requiring people to know with 100% certainty that their partner is over 16 is not what the law says.
What I have said was that if you're not 100% sure then don't go there as it's not worth the risk.
No one could ever be 100% sure in that scenario.
Driving license, driving itself, someone from work you don't know but recognise. A mate of someone from work. Someone who was at uni with a mate. A stranger but you recognise from your local vet/GP/law practice/dentist etc, yes you can be sure someone's not 15.