As I read the available information, there is ONE program director on board for the 46 or so guests. Local guides handle the touring off the ship.
In my experience the PDs are pretty adept at managing the group. Since the majority of GCT/ OAT travellers tend to be experienced and flexible, few need a lot of hand holding.
OAT groups tends to be smaller.
I will be on the Provence at the end of the month.