If I could play golf, I'd probably have been hired

What do you want? Do you want the higher role? If so, a lawyer will either tell you that you have no case, send a threatening letter, or sue your employer. The first option doesn't get you where you want to be (and will cost money due to the lawyer's fees) and the latter two options might get you the job, but won't make your employer happy. You won't be able to stay comfortably in the job for long since your employer will know that you are willing to take legal action to keep your job. Whether this legal or not is somewhat irrelevant; laws are not self-enforcing and require action on your part for your desired outcome. Do you want more pay/more responsibility? Then ask for that so that your employer has multiple ways of achieving that goal. Asking for a particular job limits the options to one; asking for a different job has multiple options. There is nothing else out there in my specialist field This is really the crux of your problem - you have no leverage. You either need to find leverage (relocate to a different area or redouble your searches locally). Until then, your employer realizes your situation and is acting accordingly.

I still did not have the leadership skills required to take over our office, which is in a delicate situation (not doing well at all, due to a multitude of factors, one of which led to the removal of the former head), but I would be recommended for the top role in a different office. This could go two ways. It certainly could be that they don't want to move you up because of your gender. But the "not doing well at all" part could be more of an issue than you realize. Toward the end of her career, my mother was in a very similar situation. After a LONG time as second fiddle, she was passed over for the head job, then passed over again when the guy they hired quit. Shortly after the second guy came on, it became apparent they'd hired him specifically because he had experience in dismantling companies, which is what happened: they closed her branch (she was the last one kept), and shortly thereafter moved her into a leadership role in another branch. Afterwards, she was told (sincerely or not) that they had wanted to hire her earlier, but that senior leadership felt it was better if the person who took the branch apart came in from the outside vs. being anyone within the organization. Based on my experience watching that unfold, I might take the "recommend for the top job at another office" as a very subtle hint, and I'd do everything in my power to get out now. Also, the recommendation of the now-demoted guy is still very valuable; do everything you can to use that. Good luck.

It's not that fishy. If you are a specialist and good at your job, they probably want you to keep doing your specialist job. It's generally easier to find generic manager type people than it is to find specialists.

Hard to tell if this is discrimination for being a woman; they may just not like you. They have a different vision for the company than the one they see you providing. Maybe they just want fresh blood (not someone who 'grew up' in the company). Your subordinates may like you but the higher ups don't want you to grow to their level. This is clear because they haven't been grooming you for any higher positions. So I would polish up my resume and hit the streets. A year ago, the position directly above mine became available unexpectedly and I filled in for the higher role for four months with hope I would be hired permanently (at no extra pay - although the higher position does pay more, I felt it might adversely affect my employment chances if I asked for the money). This was the sign - HR should have made it clear that you were getting a 'acting director' position or something like this. But they didn't give you a title - a clear sign they want someone else. But you did the work without the formal acknowledgement of some kind of title. Next time, hold out doing the work until you get the title. Even if it is "acting." Don't do the work and hope for the reward. So I repeatedly requested leadership, management and other training to enable me to fulfill the top job should the position become available, which has not been provided despite assurances. I've learned in business they really don't care about you. They want the work done, they don't care if you grow. If they're not growing you, you either grow yourself (find the training yourself & write a proposal, make it impossible for them to say no) or leave. Right now they see you as being happy with empty promises, since you haven't done anything else. I know. it sucks. You really have to take the bull by the horns. So as to your specific question, I think that if discrimination was happening here, your specific case would be hard to prove. I've seen much more obvious versions of it (woman got the role with title, then told it was provisional when she revealed she was 3 mo pregnant. I told her to lawyer up stat.) You could work with your manager 'how do I get to that role' and if it means learning to schmooze then you do that. But personally I wouldn't bother. Add'l: BabeTheBlueOx has it; they like to keep specialists right where they are doing good work.

You should consult an employment lawyer if you want to. If the department isn't doing well, you should consider whether hiring you wouldn't have been placing you on a "glass cliff". You should also consider applying elsewhere because you may never get the job you want out of these people.

Why not apply for the job that the new guy left?

I agree with many above - they want to keep you where you are. When this happened to me, it took me a while to figure it out. They said I couldn't move up because I didn't have management skills. I entered a masters degree program for management. Then it was because I didn't know all of the job duties of the people below the position. So I applied for a position in a different department. They offered it to me, but for significantly less pay than I was making. This was a place that routinely promoted buddies over better qualified people. So I started looking for a new job and found one. I found a better job with better coworkers and a better boss. And I haven't regretted it yet. My mother ran into this same situation in a different industry. She switched companies in order to move up in ranks. Then, when she hit another ceiling at that company, she switched back - but higher still on the corporate ladder. And then again. Some companies want to help their employees move up. Some don't. Sometimes you have to jump ship a couple of times just to get higher in your current ship.

Seconding look elsewhere. It's often (maybe usually) a waste of time to try and figure out the rational reasons behind hiring and promotion decisions, because there often aren't any. It sounds to me like the guy making the decisions doesn't like you. This is not something you should feel bad about, but don't continue expending effort trying to make him decide to promote you. If you find another job, odds are very good that the people there will like you (or they would not hire you), and that would make you more upwardly mobile there. I think consulting a lawyer is also a waste of time in your case. You'll never recover for management's bad decision-making, unless you can prove bias based on gender, or age, or ethnicity, or something, and it doesn't sound like your manager has been stupid enough to leave proof of that lying around. Move on.

Well, I'd definitely look for a new job, because this place seems to suck, and you can do better. And if you take legal action your place there will be pretty untenable. It won't take much time or money for a quick consultation with an employment lawyer who is familiar with the laws and tribunals in Queensland and maybe even the large company you work for. Given that you don't have any proof of illegal discrimination, I doubt much will come of it, but you really shouldn't take my word for it. Talk to an expert.