@pbdr
You can go at 55 if you want, but your pensions will be actuarially reduced for early retirement. If your colleagues don't have special class status then perhaps they just decided to take the hit of actuarial reduction and went early.
This is correct. There are tables on the NHS pension website which show you the percentage reduction for every month you take it early. There's also a simpler rough guide showing an annual reduction so if you take it at exactly 55, 56 etc.
As your pension is in 2 pots, you will need to look at the tables for both schemes. As they have different retirement ages, the impact of going earlier will be different for each.
Iirc, you had to be in the old pension scheme at the time if you wanted to choose to remain in it, so if you weren't employed in the NHS at that point, your future contributions would automatically go into the newer scheme.
If you want to know what impact retiring early would have, you can request a quote which I think you might have to pay for.
Must also warn you, that dealing with the NHS pension team is an absolute nightmare. They made multiple mistakes in my case, which if I hadnt pursued, would have cost me several thousands pounds a year. It took a formal complaint for me to get this resolved. Quotes were wrong on multiple occasions, one took over 6 months, and they started paying my (actuarially reduced) pension 4 months early. In the end I gave up trying to put that right.