Yeti Keepers of the Great Christmastide Crystal Cavern Division

  Yeti Keepers of the Great Christmastide Crystal Cavern Division is the oldest division, having only been under Santa Claus for the longest time. They accept each parliament member. They are offcially under The Christmastide Department of Security but still directly report The Clauses or the entire parliament. Mostly The Clauses.
  However, they respect every being within the Kingdom and will gather with them not just on ceremonial occasions but in everyday life.
  The Yetis have sworn an oath and have upheld it for centuries. Without any problems. They are, perhaps on purpose, the oldest of the security measures if the shield isn't counted. Especially if you say the oldest and longest-running security measure as they have protected Santa's Power Plant since 350CE.
 

Size of Agency

This division is large due to the entire Yeti Clan being the Keepers of the Great Christmastide Crystal Cavern.
 

Training

There was none in the beginning.
  However, each Yeti does agree that they would learn if Santa could bring people up north. Santa doesn't do this. He gets them to agree to go where it was cold but remote.
  Somewhere in the US or Canada, the groups of Yetis undergo training. Here, they are trained by the United States Secret Service's Office of Protective Operations and the Marine Security Company (MSC) at Camp David.
  When they travel to London, the Metropolitan Police Service's (MPS) Royalty and Specialist Protection (RaSP) branch, specifically the Parliamentary and Diplomatic Protection (PaDP) Unit trains them on their ways.
  Each Yeti had learnt, at the beginning, of all Anti-Christmas Beings in two confidental meetings.
 

Yetis as Protectors of Santa's Power Plant

The qualifications Yetis have are how they look and if they could do battle. Santa confirms these with a discussion. He actually couldn't believe they were better candidates than these beings.
  They are taller than many mortals and look tough and intimidating. If someone even accidentally comes, this is what is needed to ensure they don't ever make this mistake again. Which Nicholas was thinking the same thing. They also know who is allowed in.
  The Yetis keep a strict schedule of six hours on and then switching. Santa allows them time off in the least busy time of the year. Yetis are also off from the Winter Solstice until the day after Christmas. Except when they help with lifting the sack. During the least busy time, many elves and reindeer guard the entrance. There are days when Mrs. Claus even helps! But this is rare around Christmas when it is all-hands-on-deck.
 

Guardianship Duties

Protection: Guarding the sacred natural space and the crystals against threats, both natural and magical.
  Harmony/Unity/Friendship: Fostering the enviroment and nurturing the Christmas Spirit that sustains the power for the village and Santa's Christmas Eve Trip.
 

Origins

This detail was established a millennia and centuries ago after the formation of the Kingdom and the creation of Santa's Toy Workshop Compound.
  Throughout the following 1000+ years, the Kingdom would continue. The Yetis would watch over the cavern even when magic has gone. There were a few incidents from The Anti-Claus. And Dark Magic did try but neither succeeded. And even when it came back.