The crew would have been Captain, co Pilot beside him with the flight engineer just behind him. The normal nav is standing behind the captain (normal practice). It is clear that there was also someone in the bomb aimers position - almost certainly another nav. What a sensible precaution given the very iffy weather. On normal deployments a number of ground crew are also present but they would not have been necessary on this occasion. Some may have wished to be there, however. And why not?