Given a promotion in an interview!

This was a strange one for me, I had completely fallen out with my current employer, I needed out asap so I applied for a role at a well known chocolate manufacturer, it was a little far away to drive really but I was planning on just getting out of my current job as quick as I could and then focus on finding the perfect job after, if I needed too, so I’d applied for loads. But this one was very similar to my current job that I had a lot of experience in, even using the same software system etc and it was similar pay, around £30k at the time, so I was quite confident I’d get the job once offered an interview. At the interview I got such a relaxed vibe, it wasn’t a traditional interview really, it was basically a chat with the Production Manager as we walked around the factory and he showed me where I’d work and then introduced me to my team, I assumed I would be working with them in the same role. He then introduced me to the supervisor and we had a quick chat and that’s when it got weird, he said something along the lines of “I’m leaving in 5 weeks so we would need to catch you up as quick as possible and get the handover done perfectly so we don’t disrupt the team too much” That’s when the Production Manager told me they thought I’d be better suited to the supervisory role because of my experience and asked if I wanted the job there and then! I accepted, I gained a £15k a year pay rise over my current role and stayed there for 3 years before taking a management role at another company, where I am today, which was helped by my 3 years in a supervisory role, Mad break that turned my career around!