He tirlëd at the pin. He twiddled or rattled with the latch before opening the door. Guillaume di Lorris, in his Romance of the Rose (thirteenth century), says, “When persons visit a friend they ought not to bounce all at once into the room, but should announce their approach by a slight cough, or few words spoken in the hall, or a slight shuffling of their feet, so as not to take their friends unawares.” The pin is the door-latch, and before a visitor entered a room it was, in Scotland, thought good manners to fumble at the latch to give notice of your intention to enter. (Tirl is the Anglo-Saxon Thwer-an, to turn, Dutch dwarlen, our twirl, etc., or Danish trille, German triller, Welsh treillio; our trill, to rattle or roll.)
Right quick he mounted up the stair, And tirled at the pin.
Charlie is my Darling.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894