We also need to know more about the process.

If it's 'take the blue pill' , then it could be done in total secret without even any of the household staff knowing about it.

Lord Reggie wouldn't let on (there so has to be a character named Lord Reginald now, even if it's just a mod npc) because if he's the first to crack immortality, he'll have a huge advantage over rival lords.

Much harder to make a correlation when we don't know or even suspect that it was even done in the first place.

 

If it's 'large machine with flashing lights and wooshy sounds' , then people are going to know what lord did something weird and eventually (given hundreds of cases of undead like in most rpgs and Gromnir's point) they're going to make a connection.

 

Meh, doesn't overly bother me but it would be better to have a solid explanation if there are loads of undead in one area.

Again, we assume that there are going to gaggles of marauding ghuls wondering the streets of any town that an animancer has walked through. I assume said animancer would not be long for this world, as he would be killed and/or apprehended by the authorities, the family of his most recent client, or (most likely) other animancers who don't want to draw too much attention to themselves. 

 

Remember, the experience of the adventure is not the experience of the common person.