To feel completely overlooked and demoralised

I think in your position I would:

• Make it very clear you would like the interim position and you are willing to train up the replacement to backfill you (do NOT do both jobs - it will become permanent because you can ‘cope’ - or worse you will fail to cope.
• If they insist on going for the interim manager they have chosen, decline to do that extra bit the manager is not qualified for. They chose him/her, so their problem to sort out. Don’t make it easy for them to do what you don’t want. Find a good excuse - no capacity, can’t do it and assist new manager at the same time. Whatever sounds reasonable.
• I’d make it as difficult as possible to make me train the new person up. Again whatever works. Would they believe you don’t have time over your current job to do it? Could you claim to interim person that aspects of the job you don’t know what your predecessor did and you can’t help them they will have to figure it out as you would have to in their shoes? Why should you go out of your way to help them put in place someone else for the job you wanted and make that person look good?
• When the new manager comes I’d be sticking strictly to my job description and leaving on time. No putting the extra effort in.
• Get the reference from the previous manager and start looking for another job. They almost certainly have you pigeonholed into too useful in current job to promote. Or they don’t value you. Either one is no good long term.

I think another reason they may not want you to move up is because the ‘back-filling’ of your role if you did would probably be a huge headache for them. It’s annoying to be hardworking and a good employee and come up against these situations. All too often it’s women who find this happens to them as they’re more likely to find it harder to move roles and keep flexible working etc.

But then everyone loses out.

Look for another job, obviously do not respect you and your knowledge.

Yes, email the senior manager as above saying you're interested, experienced and qualified. Make it so they have to turn you down, rather than being able to say they just weren't aware of you as an option - whether or not that's actually true.

This. First post nails it again!

I am not sure it is constructive dismissal. They are saying it's temporary, they haven't got a policy that says they have to advertise roles (I think you said this OP) and they have offered (again I think you said OP) to pay a bit more for the additional work which requires qualification which OP has.
It really depends on whether you want to stay or not OP. You can go in and say that you want that extra title and a shot at the eventual job. You can just look for another job. But resigning without a job and going to a ET for constructive dismissal is going to take up a lot of time and effort and an uncertain outcome

Ah, okay, I get it.

Then in that case you need to highlight to your manager that, starting immediately, you will be no longer taking on any activities or tasks which are identifiable not part of your current role/job description.

I would also be raising a dispute with HR.

So, sorry if I've misunderstood your reply, but are you saying that your current manager doesn't think that you are a suitable candidate as her replacement ?

I think this is good advice 🙂

Agreed

Have you discussed this with your current manager?

Wouldn't you have expected her to already have put you forward as her replacement?

You need to work a bit in about not being suitable for the position, so you can't be a suitable person to train the person who did get the position!

Transport and general workers, there's a union for every mode of work. Constructive dismissal is very unpleasant but quite prevalent, financially driven mostly. It is basically when a boss creates exactly the reaction you've got, then acts all surprised when you quit your job. They've constructed a situation in which you leave them, so they've dismissed you without dismissing you (where dismissed equals fired). I expect you've googled it by now. It's very easy to pursue, or for your union representative to pursue on your behalf I should say. Just join a union and speak to a representative, it's very psychologically supportive and you don't have to do what they advise (I didn't. To my regret!).

Yes get a nice reference from the manager who is leaving, (can u take her out for a drink and chat over it all. But above all, not telling anyone necessarily til you got your nice reference, you can also write 'acting interim manager with dates or whatever that is just fact.) . Then I honestly think you should prefer your resignation without giving any reason just something vague like needing to regroup and or focus on your hobbies. They are possibly wanting this I've just realised you need a union representative ,-this could be constructive dismissal.

Crucial that you get your reference from your leaving line manager.

They intend to use you and don't care a whit for your progression.

Take the advice sbove, decline to be used and start job hunting.

Go out sick for a few weeks, regular illness, not stress, to drive the point home as you job hunt.

https://youtube.com/shorts/Ixy5nl-k56M?si=BGICvk7ZVPZtUbCf

Brilliant YT channel - Veronica is the woman we all need to be at work. This scenario might resonate, OP! Good luck with whatever you decide to do.

It was getting to a point of needing to for my own sanity. I was so overworked. I covered HR for 13 countries and had learned the employment law for each country which I think it's why they needed me in my role, if I moved up I would be stepping away from the day to day running of it all.

My husband was in secure employment and we have relatively low outgoings so it made it easier. I had about 10k saved up incase I needed to supplement my income but I didn't need it.
I hope you get sorted, there's so many organisations that don't think about the effects on people when they make these decisions. You just have to do what is right for you. X