Think amongst the consist is a carriage for Lizzie, a carriage for Phil the racist Greek and I think their idiot eldest son has his own carriage for when he uses the train (it doesn't get used by any of the others unless they're accompanying Liz, Phil or Charlie).
Pre-posting edit:
there's a full list of the carriage fleet post 1977 here. From that, current carriages are:
2903 HM The Queen's lounge, bedroom and bathroom
2904 HRH The Duke of Edinburgh's lounge, bedroom and bathroom
2915 Royal Household sleeping car
2916 Royal Family dining car with kitchen
2917 Royal Household dining car with kitchen
2920 Royal Household couchette, diesel generator & brake van
2921 Royal Household couchette, kitchen & brake van
2922 HRH The Prince of Wales's sleeping car
2923 HRH The Prince of Wales's saloon.
"Royal Household" will include their protection officers.