Whatever you do – whether it be addressing a Duchess or burning a village – do it politely. Exceedingly politely. Your reputation rides upon it.
You may be coping with relatives at a holiday dinner, or an influx of heretics, or scam calls at dinner time. Whatever occurs, do not lose your ability to be polite. You may curse and rage inwardly, but do not let the least sign of it be seen in your eyes or heard in your voice.
Polite conversation is often thought to be all of felicity – yes, yes, and yes always. It would be pleasant to think this, but what of the times when morals and discretion prohibit agreement? How can one say ” no ” in a kindly fashion and have it actually stick to the door?
Simply use the politeness of a bygone age. Regret that you cannot do as requested. Be devastated that you cannot accede to such reasonable demand. Give a thousand apologies…you can give them in a batch or one by one and you’ll wear out the most persistent requester. The ability to weep softly upon demand is a major social skill.
Speak in the third party. When asked for money say that the Chancellor of the Exchequer would never agree. When asked for practical help mention an old war wound and wince your way out of the room.
The basic goal is to leave the other person with a vague feeling that they have somehow transgressed and need to make amends. Accept their apologies and reparations gracefully.