Sir Tiffy Cashien sits in the Falador Park, and he is head of recruitment for the Temple Knights, a division of the White Knights. He is also where one can start the Recruitment Drive, Wanted! and The Slug Menace quests. He sells Initiate armour, Proselyte armour and can change the player's respawn points to Falador using the Gaze of Saradomin.
As with many White Knights, his name is a play on words. It sounds like "certification" if said correctly.
He is also the only White Knight that speaks with the stereotypical British vernacular, as noted by the words he says (e.g. What Ho!, Don'tchaknow).