Do NPC armies actually gain XP?

[Weaver]

obviously lords do gain levels, which is pretty cool.
but i suspect there to be an extra level of coolness because it seems that lords' armies also gain XP. i'm not absolutely positive about that, but i've recently encountered a few camp followers in lord's army. as you all know there are no army types on the world map that include camp followers. naturally i concluded that those girls evolved from peasant women whom the lord freed from bandits.
what do you guys say? maybe i'm missing something?

 

[Gilrain]

I've never noticed this, although I haven't really looked.  I'm going to be keeping a closer eye on lord's parties now.

 

[italiano]

The npc parties don't level up the same way as the game won't keep track of every troop in the game, but I do think they do have their troops upgraded.