This guy in uni halls keeps pestering me for sex

I take it this is "his sleazy mate" you referred to in post #9?
If that's the case, then it's possible that given what's happened to the original guy, it may make him think twice about his actions. At the very least, it shows that the rest of you won't just put up with it, and won't be afraid to act on or report any bad behaviour.
TBF, we're only aware of these two individuals who are confirmed sex-pests... for all we know, the other guys in the block could be decent lads who respect peoples boundaries and understand when "no" means "no". Also, we don't know if this other guy will go to the same lengths as the first one. Obviously, it depends on their specific actions, but in the first instance, I would say a firm verbal warning (either from one of the good-guys on the corridor, or a more official presence like a hall warden) would be adequate in the first instance... before going down more formal routes involving university officials or police.

I take it this is "his sleazy mate" you referred to in post #9?
If that's the case, then it's possible that given what's happened to the original guy, it may make him think twice about his actions. At the very least, it shows that the rest of you won't just put up with it, and won't be afraid to act on or report any bad behaviour.
TBF, we're only aware of these two individuals who are confirmed sex-pests... for all we know, the other guys in the block could be decent lads who respect peoples boundaries and understand when "no" means "no". Also, we don't know if this other guy will go to the same lengths as the first one. Obviously, it depends on their specific actions, but in the first instance, I would say a firm verbal warning (either from one of the good-guys on the corridor, or a more official presence like a hall warden) would be adequate in the first instance... before going down more formal routes involving university officials or police.

A hall warden is a university official and the blanket warning can be through an email to all residents in the block. It does not have to be specific to the male residents.
Also, i wont advise ‘one of the good guys’ to issue a firm verbal warning. We don't know how the other guy(s) would react and things can get ugly fast esp between young guys.
Informing the police is also for the OP and other women’s safety in the block. They can keep tabs on the guys who have complaints. For example, one of the guys can return to campus to harm one of the girls. Hopefully not, but it happens. If they know that the feds are aware, they would probably think twice.

A hall warden is a university official and the blanket warning can be through an email to all residents in the block. It does not have to be specific to the male residents.
Also, i wont advise ‘one of the good guys’ to issue a firm verbal warning. We don't know how the other guy(s) would react and things can get ugly fast esp between young guys.
Informing the police is also for the OP and other women’s safety in the block. They can keep tabs on the guys who have complaints. For example, one of the guys can return to campus to harm one of the girls. Hopefully not, but it happens. If they know that the feds are aware, they would probably think twice.

Also, i wont advise ‘one of the good guys’ to issue a firm verbal warning. We don't know how the other guy(s) would react and things can get ugly fast esp between young guys

Informing the police is also for the OP and other women’s safety in the block. They can keep tabs on the guys who have complaints. For example, one of the guys can return to campus to harm one of the girls. Hopefully not, but it happens. If they know that the feds are aware, they would probably think twice.

Most of the guys are good here just a couple that spoil it

At my sisters uni, turned out their Warden was a sex pest himself and took advantage of a girl so drunk she was basically passed out

Yeah, I get what you mean... without referring to specific incidents the warden could send out a generic letter stating that sexual harassment will not be tolerated on their premises and a polite reminder about consent and boundaries (it's mind-blowing that fully grown adults should need this pointing out, but this way it covers everything). IMHO, an email can easily be missed or overlooked, so a printed letter placed under each persons door would be harder to miss. And for the record, although a hall warden is a university official, it won't have the same gravity as a report from the main universities HR department.
I take your point... but the OP knows the individuals and would be in a better position than either of us to speculate on how they would react; the OP seems reasonably intelligent, so can trust their judgement on whether or not this approach is a good idea. On this point, I would reiterate the point I made in my reply #12 on here; i.e. it's important for all to remain calm, in control and not let emotions get the better of them.
I agree... what you're saying makes perfect sense... but it's the OP's decision on where they go from here.
Unfortunately, you're always going to get a bit of that IRL. Granted, they won't always be as extreme as this or of this nature, but we're going to have to deal with unpleasant people or individuals we don't like in places like work etc. You'll learn through experience how to effectively manage or deal with these kind of people.
Although this may sound scary, I think you need to treat this as a "one-off" incident; I'm not aware of any other warden abusing their position in this way (assuming she was in his halls). Most wardens are employees of the University of some capacity (e.g. lecturers), and so would face severe consequences if such an allegation can be proven.

I wouldn't call 18, 19 or 20 year olds as fully grown adults. These are people who were recently given freedom to live as fully independent individuals esp if they were probably in boarding schools for the past 5, 7 or several years of their lives. Besides, many of them would be drinking for the first time, taking class As or Bs, having sex or doing foolish things, so the allure and excitement can be a bit too strong for some.
Also, i do not think the University’s HR department would intervene in that manner as the students are not employees of the institution. But i understood your point.
Yes, you are right that the OP would know the situation better than both of us. However, some people do not like being confronted in certain ways and their reactions could be tricky to handle especially coming from other people that they consider as peers.
Finally, I take your point that it’s the OP’s decision on how to proceed but, if she is harmed, the next reasonable set of questions would be “why didn't she report to the police?” and “why did she remain in her current uni accom?”.
People, in my view, are generally advised to put such matters on the radar of the police authorities. That way, if the lad goes on to demand for sex from other women in other settings away from the uni, his profile is flagged quicker and more efficiently.

Also, i do not think the University’s HR department would intervene in that manner as the students are not employees of the institution. But i understood your point.

Yes, you are right that the OP would know the situation better than both of us. However, some people do not like being confronted in certain ways and their reactions could be tricky to handle especially coming from other people that they consider as peers.

Finally, I take your point that it’s the OP’s decision on how to proceed but, if she is harmed, the next reasonable set of questions would be “why didn't she report to the police?” and “why did she remain in her current uni accom?”.

People, in my view, are generally advised to put such matters on the radar of the police authorities. That way, if the lad goes on to demand for sex from other women in other settings away from the uni, his profile is flagged quicker and more
efficiently.

Sorry, but I don't accept that argument that people at that "studenty" age (i.e. 18-21) aren't fully grown adults. Don't get me wrong, I'm not getting at you personally, but I hate the tendency (on this board in particular) for people to wrap them up in cotton wool and think they need this super-ultra protection from the "Big bad world".
According to the law, you are considered an adult at the age of 18; not just in the UK, but in just about every major country in the world. At that age, you can get married, have a say in who governs the country... you can even join the armed forces and put your life on the line for your country. Whilst I do accept they may still need to acquire the wisdom, experience and maturity of older adults, let's not forget that (according to the law), you're criminally responsible from the age of 10 years old. In addition, if they are going to flee the nest and stand on their own two feet, I would expect them to know how to conduct themselves around other people, especially those they have to share a communal area with. Furthermore, if an 18 year old doesn't know the difference between right and wrong, then the educational system has failed them and we've got a bit of a problem.
If you can't do the time, don't do the crime.
Fair comment, I should have said the University Students Admin department instead.
As per my previous posts, I agree and think that the OP should inform the police... but it's not my decision to make that.
Reporting these kind of things can still cause a certain amount of trauma from the victim, and they have to ask themselves if they're willing to go through it all; especially if the evidence is somewhat sketchy or circumstantial. It's easy for us (as observers) to say that the OP should do this, that and the other, but it's the OP who'll have to live with the aftermath of it all.
Ultimately, I think they need to do a risk assessment. The fact that the perpetrator has voluntarily left the university (when they had the option of only moving halls, but could remain at the uni), would suggest that he's a low-risk to the OP, at least. Even if he did come back, he no longer has access to the block, and I presume there's a significant CCTV presence as well.