The term 'mutton dressed as lamb' was first used in the journal of social
gossip that Mrs Frances Calvert compiled in 1811, and is possibly attributed to the then Prince of Wales (later George IV). At a musical
evening, the Prince was asked whether he did not think some girl
pretty. He reputedly answered, “Girl! Girls are not to my taste. I
don't
like lamb; but mutton dressed
like lamb!”
In this case, ‘dressing’ refers to the preparation of
food before cooking. The implication in 'dressed as lamb' is that the woman has prepared herself for a romantic encounter. 'Mutton dressed as lamb' was originally a disparaging description of a woman aiming to deceive men into believing she was younger than she really was; back then it was an economic necessity for a woman to marry while still of childbearing age.
Nowadays it refers exclusively to a woman who is deluded and thinks herself attractive in clothes, jewellery and make-up usually worn by those much younger. She’
s probably looked in the mirror and thinks herself sex on legs, but she merely proves that eyesight deteriorates with age.
