The words Prince William and Kate Middleton won't say

How posh are you? An expert reveals the words making you sound common that you'd never hear William and Kate say. Photo / Getty

You may dress the part and have the accent to match but the vocabulary you use also speaks buckets about your social standing.

Indeed, according to social anthropologist and author, Kate Fox, there are certain words that are making you sound common - and they'll surprise you.

From "toilet" to "dinner" and even the word "posh" itself, Kate reveals the words that are infallible ­indicators of your class - and according to Diply, who rounded them up, you'll never catch the Duke and Duchess of Cambridge uttering them.

1. Mum and dad

The upper class refer to their parents as "mummy and daddy", which Prince Charles proved when he dubbed the Queen "mummy" in a speech in honour of her Diamond Jubilee.

2. Toilet

According to Kate, this term is detested because of its French origins. The royal family apparently say "loo" or "lavatory" instead. Kate says you should never use the terms "gents", "ladies" "bathroom" or "powder room".

3. Posh

Ironically, this is a word that should never be used by the upper class, says Kate. She says it is used in a jokey manner by upper classes to describe those outside of their circles. Royals use the term "smart" instead.

4. Pardon

Apparently "pardon" is a curse word in royal circles. Instead plump for "sorry" or even "what".

5. Portions

Describing a serving of food as a "portion" is apparently more commonly used among the lower and middle classes. Upmarket people apparently call it a "helping".

6. Perfume

Those in the upper classes dub it a "scent", not a perfume or fragrance.

7. Lounge

Royals don't have a lounge. They have a "drawing room" or a "sitting room". "Living room" is equally as frowned upon.

8. Dinner or tea

Hailing your evening meal "tea" is apparently one of the biggest working-class indicators. According to Diply, the higher echelons call this meal "dinner" or "supper".