What UK dress size is a woman with a 33 inch waist?

In the UK a size 10 dress or skirt has a 28 inch waist and sizes go up in increments of 2".

Size 12 would therefore have a 30" waist, size 14, a 32" inch waist, size 16, a 34" waist, size 18, a 36" waist and so on. For a waist 33" you would either have to settle for a size 14, with a 32 inch waist, or go one larger and get a size 16, which would have a 34" waist.