I’ve really messed up at work

This. Plus flagging up the mismanagement of the big boss. I don't think the OP actually wants to hear any of this. Good luck to her I say.

Yes, I do understand and that all makes perfect sense in the real world. And I know you are trying to be sensible and probably smart too. But no good deed goes unpunished. Like it or not you have threatened the position of the big boss. You've basically called them inefficient. Why do you think she/he is "fuming"! Surely you get that on some level?

I have been in your position OP.

I worked years ago for a very large company and was placed in X Dept and was fine there, learnt the role and was getting on great. They then moved me to Y dept as a lady was going on maternity and I was to apparently be her cover. There was only me and another guy going to be doing this job.

Well I say there bored shitess all day. Nothing to do at all. I couldn't even make work to do. I spoke to my old manager and she said they must just be a little quiet and it will pick up as the two there previously were always busy.

I gave it another 6 weeks of literally doing nothing, working maximum of an hour a day unless I helped out my previous department. As such I offered to float between the two as at least I wouldn't be so bored but was categorically told no, no not happened and they seemed angry I offered.

It was the most money I'd ever earnt in my life and it was hard to walk away from that but boredom is no joke! I spent hours picking my weekly shop online from Sainsburys just for something to do!!

HOW the two in the department made it a full job each when it wasn't even one job is beyond me 😂

so you want to take others work
they are too busy to do so but it is part of their job description but you have come in and want to make changes to the job descriptions
and t hey dont like it

Perhaps to salve your conscience you could have unofficially offered to help your colleagues on an ad hoc basis, while not making it clear to your boss that you were consistently under employed. Now you have a target on your back for rocking the boat.

Oh my dear why were you not a little more wise?

Exactly.

@ohbuggera "I haven’t pointed out that other people aren’t doing much. I’ve just pointed out that I feel I could do more."

Bit naive OP. If you aren't doing much it stands to reason that a shed load of other people aren't either. So you've basically flagged up spectacular inefficiency. The big boss will naturally feel incredibly threatened with any suggestion of mismanagement or over-staffing which could lead to job cuts. Especially their own or their cronies!

In your position I would have kept my head down and my mouth shut. I would have written a novel or run an Ebay shop in the unused time.

I once had a similar sounding job where I could get through a full days work in about 2 hours. I asked my manager for more to do and was denied. It was so boring. I didn't have a window to stare out of so started reading. Literally sitting at my desk reading a book for 6 hours per day. Totally ridiculous but continued for a couple of months until a director wandered through my section. We talked, no anger, and within about a day I was assigned to help out another department as and when I could. Still remember sitting there reading Catch 22.

If only wfh was a thing back then. Would have been a dream! I can see why the public sector are so keen on it.

Boredom at work is bad for my mental health.

I would not say, "this job can be done in a day," but, "I have a bit capacity,, are there any reports/rotas/other pieces of work I could get involved with to ease up your workload?"

If there is nothing forthcoming, I would look at:

• Is there anything in the department i can do to improve procedures. Probably not, if you're not that busy anyway, but no harm in looking at any annoying processes.
• Is there any online training I can do (there's always technical training for us. Or how to write AI prompts or something)
• Is there any work shadowing i could do in another department that I'm interested in? I know you've been told you can't get involved in other departments, but you can network and ask about them, and then inform, rather than ask permission...
• Are there any employee groups I can get involved in, e.g. women's network or similar?
• Is there any mentoring I could be involved in?
• Is there any volunteering I could be involved in? (e.g. we have links to a locsl school, where we can be involved I mentoring Y9s and CV workshops and things,)

If there’s really nothing (don't believe that, but human barriers can block things,) then I'd spend the time updating my CV and looking around for places who can make decent use of me.

I suspect the problem is that you've highlighted mismanagement at a higher level, OP. But you should never be ashamed of acting with integrity. Hope things work out, and if they don't, private-sector jobs would appreciate your efficiency.

It may not be possible to work across more than one department, would you expect to be in charge of two different departments? Or in charge in one and in a junior role in another? I think you have been lucky to be in charge of even a small department after a year.

You may be making them look inefficient and you are implying the person who's job you are now doing wasn't working to capacity. I would wait and see what they actually say. You definitely need to be diplomatic about the colleague you took over from, unless they left under a cloud, if they were promoted for doing a great job it could be a particular problem.

They may also be thinking you only just joined and now think you know it all and are not grateful for your current role.

You're upsetting the apple cart. You make your predecessors and their managers look bad by saying you can do the job in a day. It makes you look like a braggart as well. You may be talented and hard working but you don't have any idea about the politics of work in the public sector. You'd do better in the private sector but even there you do need to consider the politics and wider context before you speak out. You should have used the extra time to study and improve your grasp of politics!

Oh, I work in public sector in another country and this absolutely the way this stuff can go here too. I have every sympathy!

That said, I do think you're right to raise. All it takes is another manager to point to the job at some point in the future when they need to make cuts and there goes your job.

Just be as calm and neutral in the meeting. I would emphasise everything you've said about how you like to have a lot going on, how you'd like to help other teams etc. Then if she has to justify changes further up the chain why you need more work and she'd allowed the previous manager to stretch it to a full-time job, it gives her the "out" of saying that you're such a go-getter you specifically needed more to do.

Classic public sector. It’s not for everyone. Including me.

You’ve flagged that you have capacity in a totally reasonable way.

If a senior staff member reacts in a way that’s unhinged, you should consider if this is a professional culture that you can thrive in, or if you should work elsewhere.

You can ask in different ways though…

I wouldn't bet on this. One manager when I told them I had capacity to take on more and suggested I approach other managers in our section who I knew had overstretched teams to offer my services, he went red in the face with rage and forbade me from contacting them.

In a different job when I told the manager there was not enough to fill my time she just shrugged and said ' well this is the job.'

It seems unprofessional that she would be openly so angry.
Until you understand why she is angry it’s hard to advise.
Anger shouldn’t usually feature in the workplace and is a bit of a red flag, to be honest.

It is very unwise to go up the chain and say your job takes a day and you can take another job.
one, this makes you vulnerable for redundancy etc.
why would they pay you 5x time more?

two, lots of managers are empire building. They want to increase headcount not decrease it. Your message is very unhelpful to their goals.

you should be more clever and frame it more strategically next time - that you improved efficiency by doing XYZ and now have more capacity to take on ABC - essentially to take over more work as a manager and increase your scope

not sure there will be next time here although you can try to salvage the situation by reframing it as above