Just some thoughts.
3rd Imperium
Just judging from the types of craft and the supplements describing the Imperium and its nobility, I'm guessing that each member of the Moot is responsible for his own transport to and from capital, hence all the Yachts, in core Traveller books and other supplements like Dilettante. Most of the designs are interesting (definitely useful for adventurers etc.), but seem lacking in proper support for a member of the bureaucracy and even a minimum of support retinue - only butlers and maybe one or two friends or personal aides seem to make it into .
I'm guessing that those without the means to own their own multi-megacredit jump capable pleasure palace hitch rides on naval and scout ships going in that general direction, or buy high or mid passages all the way. "You want HOW much for transport of me and my staff to Capital? I could by my own ship for that! And I could fly it too! I'm not such a bad pilot myself!"
But what if the Emperor summons you to Capital? What if the Emperor dispatches someone from Capital with an Imperial warrant, or needs to put in place a diplomat, such as an Ambassador that can talk with Imperial Authority with the Zhodani on Zhdant, the Hiver on Glea, or the K'Kree on Kirur (The Imperium seems to keep its main embassies with major Aslan clans and K'Kree on Capital, so others might do the same). They might travel as far as the border with an escort of Tigris Class Dreadnoughts if the Imperium's been a bit testy of late, but what do they fly once past the border if allowed entry? I would also assume that if a change in Ambassador is made, some allowance would also have to be made for the transport of his or her personal staff and/or the evacuation of staff being relieved of their duty/office.
"If this is a consular ship, then where is the ambassador?" Wait, wrong millieu. I meant, "If there is an Embassy, then were are the Consular Ships?"
I think there's room for few classes of vessel strictly used for and by the Imperial Bureaucracy, especially Foreign Affairs and Ministry of Justice. A limited warrant might grant access and use, often for years at a stretch, but not ownership of these vessels, retaining them for strictly Imperial business. You may be traveling in style, but that's the Emperor's property you're walking around in, so don't scuff the finish please.
High Level Bureaucratic Missions
The standard design should not too big to disturb the foreign hosts it has to visit, but not necessarily unarmed. It would have to be big enough to carry not just the noble, but also enough staff for him to do the job he's required to do at the destination, if its not already waiting for him. Ideally, these should be no slower than J-4, armed but not excessively so, to allow host-state entrance. Maneuver drives may or may not be a priority (probably 1 G would be fine) if the Imperium is footing the bill for fuel at each port along the way, no transit time need be spent wilderness refuelling. At TL15 n 800-2000ton design should be just big enough to cover the basic amenities for one to two nobles (luxurious, without the lavish waste of space the yachts tend to have), a small ship's guard, and a double handful of staffers, an modest but well appointed office/lounge/dining room for audiences with foreign dignitaries (barring the K'Kree and other claustrophobic races).
Emergency Diplomacy
If, in the case of important treaties or Imperial Agents handling the end, beginning, or even curtailing a war before it starts, support staff can be cut to a minimum and a minimum of Jump-6 can be worked into the vessel. Unlike the Imperiallines transports, these vessels would be obvious official Consular ships, and help keep the former's low profile. For these ships, excess staff are even more at a premium - these are primarily express Imperial transports on strictly Imperial business. If more staff than the ship can carry are needed more of the class can be dispatched or, as is more likely, they'll follow up in the former, slower class of ship in due time to supplement the faster ship's compliment of diplomats. Another, less tasteful option, is to load up the J-6's minimal cargo space with robotic staff to tide the mission over until live staffers can arrive.
An older J5 variant of the J6 might still be in service, with several allocated to bureaucracies at the Sector and Region level across the Imperium, especially in the border regions, where changes in leadership may have to be changed at a moment's notice at the pleasure of the Sector Duke or Archdukes, with the Emperor's blessing.
Note, these ships aren't meant for low level staff positions, which would more than likely either be hired on site, or transported more slowly with much less grandiosity.
Milleu 0
More than likely, the early Imperium transported the vast majority of its diplomatic nobility in the grandest, most intimidating (or reassuring, if you've already signed the papers), fashion possible - in massive battleships. If playing in a 'stretched thin' campaign, destroyers or even armed scouts could transport a diplomat to a given neighboring pocket empire.
By a few years in, when the wealth of the Imperium is showing signs of becoming the overwhelming economic juggernaut that it is, the first purpose built consular ships are probably built, probably ranging between 500 and 800 tons, ranging Jump 3, and sporting enough luxury and posh to be considered state-owned yachts, on par with the local dictator's luxury boat, but assigned to a member of the Imperial Bureaucracy as a symbol that the Imperium can afford such things as a trifling matter, ce n'est pas grave.
These ships would also likely either be highly armed Q-ships for getting the hell outta dodge in a hurry, or fostering 'barbarian regime changes' at gunpoint while the staff looks the other way, or be supported by 1-2 equivalent tonnage escort ships. Where possible, such a design should include a decent sized bay for carrying beads, laser rifles, high tech knickknacks , and other things to gift or trade with more amenable states.
3rd Imperium
Just judging from the types of craft and the supplements describing the Imperium and its nobility, I'm guessing that each member of the Moot is responsible for his own transport to and from capital, hence all the Yachts, in core Traveller books and other supplements like Dilettante. Most of the designs are interesting (definitely useful for adventurers etc.), but seem lacking in proper support for a member of the bureaucracy and even a minimum of support retinue - only butlers and maybe one or two friends or personal aides seem to make it into .
I'm guessing that those without the means to own their own multi-megacredit jump capable pleasure palace hitch rides on naval and scout ships going in that general direction, or buy high or mid passages all the way. "You want HOW much for transport of me and my staff to Capital? I could by my own ship for that! And I could fly it too! I'm not such a bad pilot myself!"
But what if the Emperor summons you to Capital? What if the Emperor dispatches someone from Capital with an Imperial warrant, or needs to put in place a diplomat, such as an Ambassador that can talk with Imperial Authority with the Zhodani on Zhdant, the Hiver on Glea, or the K'Kree on Kirur (The Imperium seems to keep its main embassies with major Aslan clans and K'Kree on Capital, so others might do the same). They might travel as far as the border with an escort of Tigris Class Dreadnoughts if the Imperium's been a bit testy of late, but what do they fly once past the border if allowed entry? I would also assume that if a change in Ambassador is made, some allowance would also have to be made for the transport of his or her personal staff and/or the evacuation of staff being relieved of their duty/office.
"If this is a consular ship, then where is the ambassador?" Wait, wrong millieu. I meant, "If there is an Embassy, then were are the Consular Ships?"
I think there's room for few classes of vessel strictly used for and by the Imperial Bureaucracy, especially Foreign Affairs and Ministry of Justice. A limited warrant might grant access and use, often for years at a stretch, but not ownership of these vessels, retaining them for strictly Imperial business. You may be traveling in style, but that's the Emperor's property you're walking around in, so don't scuff the finish please.
High Level Bureaucratic Missions
The standard design should not too big to disturb the foreign hosts it has to visit, but not necessarily unarmed. It would have to be big enough to carry not just the noble, but also enough staff for him to do the job he's required to do at the destination, if its not already waiting for him. Ideally, these should be no slower than J-4, armed but not excessively so, to allow host-state entrance. Maneuver drives may or may not be a priority (probably 1 G would be fine) if the Imperium is footing the bill for fuel at each port along the way, no transit time need be spent wilderness refuelling. At TL15 n 800-2000ton design should be just big enough to cover the basic amenities for one to two nobles (luxurious, without the lavish waste of space the yachts tend to have), a small ship's guard, and a double handful of staffers, an modest but well appointed office/lounge/dining room for audiences with foreign dignitaries (barring the K'Kree and other claustrophobic races).
Emergency Diplomacy
If, in the case of important treaties or Imperial Agents handling the end, beginning, or even curtailing a war before it starts, support staff can be cut to a minimum and a minimum of Jump-6 can be worked into the vessel. Unlike the Imperiallines transports, these vessels would be obvious official Consular ships, and help keep the former's low profile. For these ships, excess staff are even more at a premium - these are primarily express Imperial transports on strictly Imperial business. If more staff than the ship can carry are needed more of the class can be dispatched or, as is more likely, they'll follow up in the former, slower class of ship in due time to supplement the faster ship's compliment of diplomats. Another, less tasteful option, is to load up the J-6's minimal cargo space with robotic staff to tide the mission over until live staffers can arrive.
An older J5 variant of the J6 might still be in service, with several allocated to bureaucracies at the Sector and Region level across the Imperium, especially in the border regions, where changes in leadership may have to be changed at a moment's notice at the pleasure of the Sector Duke or Archdukes, with the Emperor's blessing.
Note, these ships aren't meant for low level staff positions, which would more than likely either be hired on site, or transported more slowly with much less grandiosity.
Milleu 0
More than likely, the early Imperium transported the vast majority of its diplomatic nobility in the grandest, most intimidating (or reassuring, if you've already signed the papers), fashion possible - in massive battleships. If playing in a 'stretched thin' campaign, destroyers or even armed scouts could transport a diplomat to a given neighboring pocket empire.
By a few years in, when the wealth of the Imperium is showing signs of becoming the overwhelming economic juggernaut that it is, the first purpose built consular ships are probably built, probably ranging between 500 and 800 tons, ranging Jump 3, and sporting enough luxury and posh to be considered state-owned yachts, on par with the local dictator's luxury boat, but assigned to a member of the Imperial Bureaucracy as a symbol that the Imperium can afford such things as a trifling matter, ce n'est pas grave.
These ships would also likely either be highly armed Q-ships for getting the hell outta dodge in a hurry, or fostering 'barbarian regime changes' at gunpoint while the staff looks the other way, or be supported by 1-2 equivalent tonnage escort ships. Where possible, such a design should include a decent sized bay for carrying beads, laser rifles, high tech knickknacks , and other things to gift or trade with more amenable states.