Difficult to move up the ranks as many people in this business stay for a long time. Thus there are few openings in senior positions.
There seems to be reasonable opportunities for promotions, but you may have to be patient. The company is offering a lot of secondments now and these can be good opportunities.
I find performance and commitment is well recognised, and promotions occur when deserved (i.e, there are no "rules" about when it cannot happen).