plum in one's mouth

Pulse 108, appetite good, bowels regular, utterance thick and indistinct, speaks as if he had a plum in his mouth, walks with his legs wide apart, does not stagger, not dirty, has control over sphincters.

Georgy, "Jersey" to his masculine mates, liked Elizabeth, even though she spoke with that incredible plum in her mouth that made her sound like the Queen of England, though sometimes it was the Queen in her most private of moments: