I’m currently reading Rebecca by Daphne DuMaurier. There is a cocker spaniel called Jasper in it and all I can say is that Ms DuMaurier MUST have owned cockers. When the narrator first meets Jasper, he immediately adopts her in true cocker fashion, butt a-wiggle, tail a-thumping, thrusting his muzzle into her hand, settling with his nose on her knee fora thorough ear stroking.
Later in the book, they are walking on a beach and the dog gets ‘lost’ - they can hear him barking from another cove and they go to rescue him. They find Jasper barking at a poor unsuspecting man for NO REASON. When they try to get Jasper back he plays the ‘keep away’ game and the narrator bemoans the dog being ‘infuriating’.
Sounds exactly like a cocker to me!