I have never seen senior staff from the ship around at check in Southampton.The staff at the terminals are employed by Intercruises They are not Cunard / Carnival employees. They are the gatekeepers to the operation . If they say you need to wait outside for your turn you have little option but conform unless you have a valid reason for not. No one is suggesting a negative approach but reminding people that boarding times are being more strictly enforced in Southampton these days so the old maxim of turn up when you like no longer applies. W C Priority boarding gets you your own check in desks so the wait may be quicker but doesn’t give you necessarily an earlier boarding time , just priority when you get there for your allocated time.