have a plum in your mouth

have a plum in (one's) mouth

To speak in a manner that is indicative of a high social class. Primarily heard in UK. Because he always sounds like he has a plum in his mouth, none of us working-class sods can stand to listen to him.
See also: have, mouth, plum
Farlex Dictionary of Idioms.

have a plum in your mouth

have a rich-sounding voice or affected accent. British
See also: have, mouth, plum
Farlex Partner Idioms Dictionary
See also:
  • have a plum in (one's) mouth
  • a plum in (one's) mouth
  • a plum in your mouth
  • plum
  • speak with a plum in (one's) mouth
  • north and south
  • air of pretension
  • put words in (one's) mouth
  • put words in someone's mouth
  • put words in/into somebody's mouth