I am 27! - but you can get onto the course up to 29 (ie not yet 30). I imagine that I will be one of then older cadets, but there are others my age and some even older. It just happened that way for me. Would I change it, I don't know, probably not. I have had some great experiences working for a small company leading my own team, then moving into the City. I just know that I don't want to do this for another 5/10/15/20 etc years!. Going to miss the salary though haha.
I hope that helps
S