Summary: I have been in the same position for 7 years, and highly rated during each performance review. I am being passed over for promotion, and my manager doesn't give me clear plan for improvement. How I can convince my manager that I deserve a promotion?
A bit of background: unlike (I'm guessing) most people on StackExchange, I don't come from a tech background, but two years ago I started teaching myself Python. I work with data but in quite an old-fashioned, inefficient way (this is an industry-wide issue). Originally I saw coding as a way of automating repetive processes, and I've written scripts that save my team a fairly considerable amount of time per week. As my skills have improved I've found ways of innovating and adding value to our output. I'm no by means an expert but I know enough to make a tangible difference to my department.
We recently had a change of management team, and I interviewed for the role of senior manager. (The entire team was invited to apply; I was never a realistic possibility for the job.) Part of the interview was to present a vision of our team in the future, and I went heavy on my coding skills and what benefits they could bring. I didn't get the job but I was told that the panel were impressed by the vision I laid out, so next week I'm presenting to my new senior manager, plus other members of upper management. There's been talk of giving me a budget to lead a project developing these ideas.
So far so good. My issue is how best to treat this as a way to develop my career...
Backstory: I've been in my role for seven years and I've never really developed. Our annual reviews are scored 1-3, and in the last four years I've scored a three every year. Without wanting to place too much importance on a fairly arbitary score, that suggests to me that I'm a good performer. Despite that I'm still one of the most junior members of our team. Over the last two years roughly half our team have been promoted, one way or another, and I'm on the half that hasn't been. Ouch.
Our now ex-senior manager allocated our work, and I found him very vague and evasive whenever I spoke about development. I offered to take on more work at a higher level - that was important work so it needed to go somebody more experienced. I asked if I could shadow seniors and learn - there was no point me doing that because I was already performing well. I asked what other people were doing to progress and how I could do those things - I just needed to be patient and realise that there were people ahead of me. The coding work I was doing was a complete irrelevance to him, even when it was demonstrably improving the things our team did.
So after seven years in the job I'm one of the most junior members of the team (in tenure as well as responsbility; it's an extremely stable team and there are only two people in a team of 15 who've been here less time than me). But if this project goes ahead and it goes well, then I'll have delivered a major project with clear, provable benefits at practically no cost, and I'll have done it with skills that are unique in my team.
Given that, what's the best way for me to discuss the future of my role with the new management? I don't want to be aggressive and make demands based off a nice PowerPoint, but if I deliver then I'm far surpassing my job description and pay scale. After seven years of failing to make progress, and not getting a clear answer why, I'm starting to feel a bit fatalistic. What's a reasonable way for me to bring up these concerns and get an idea of where success in this project might leave my standing in the team and my career?