Mick: The Kendricks school. It's where the British Men of Letters train their operatives. It's like our--
Sam: Hogwarts?Mick: Exactly. Kendricks has the largest collection of occult lore in the world.
Kendricks Academy is where the British Men of Letters are taught and trained. It is located "somewhere outside London, England." It superficially resembles a wealthy public school, where the pupils wear suits and gowns.
The crest of Kenricks Academy is Vis unita fortior which roughly translates to "united strength/force is stronger." The coat of arms includes an Aquarian Star, a rampant lion (in heraldry, a symbol of bravery and nobility), and two crossed keys (the crossed keys represent the Keys of Heaven and can also be seen on the papal coats of arms). Notably, in the Kendricks Academy crest, it is facing to what is called the sinister side.
Not much is known of what the British Men of Letters "Code" entails, other than the prescription that if an agent of the Men of Letters is killed, the offending party must be executed, regardless if the death was an accident.
The Code also calls for an initiation ritual for new recruits wherein two potential members are locked in a room with a knife or dagger and must fight to the death until only one remains. This is done to see which students will move on to the next step of training, as well as gauging the loyalty of cadets to the British Men of Letters cause -- making sure they will employ their skills and execute orders without question.
After a skeptical Dean questions Mick Davies' knowledge of werewolves, Mick explains that he did extensive research on lycanthropy at Kendricks. Mick goes on to tell an impressed Sam that Kendricks holds the largest collection of occult lore in the world.
In 1987, a young Mick Davies is called to the office of the Kendricks headmistress, Dr. Hess, along with his friend Timothy. There, Dr. Hess congratulates the two boys for their hard work in passing the trials set forth by the British Men of Letters. She tells them of the important work that the British Men of Letters do, and that the time has come to learn which of the two boys moves ahead to the next level of training. She places a dagger on a table and leaves the two boys in the room, telling them only one can make it out of the room alive.
As Timothy tries to talk Mick into just running away, Mick tells him to close the door as he picks up the dagger and apologizes to his friend before killing him. Exiting the room, Mick meets Dr. Hess in the hallway and tells her that Timothy fought well and that he didn't want to die, but Dr. Hess justifies Mick's act by referencing the Code and congratulates him.
While hiding under the guise of "Alexander Ketch," Arthur tells Sam and Dean that he and his twin brother attended Kendricks Academy, but Alexander fled when he was about to become initiated to the organization because he felt it wasn't for him, bringing shame to the Ketch family. Sam, using a hard drive he stole from the British Men of Letters' American base of operations, is able to look up their academic records to confirm his account, but Dean is still suspicious of Ketch. Later, Ketch confirms that he planted the documents into the academy's servers to trick Sam and Dean.