S   M   L
PTP
16" 17" 18"
Waist 12.5" 13.5" 14.5"
Hip 18" 19" 20"
Length 32.5" 33" 33.5"

*Model (wearing Mauve) is 1.73m, UK 4/6 (PTP15.5", Waist 12", Hips 17.25") wears size S.
*Model (wearing Off-White) is 1.64m, UK6 and wears size S.

If you are in between sizes for PTP, it is best recommended to size down. 
If you are in between sizes for waist, it is best recommended to size up. 

*In between sizes refers to your measurements falling between 2 sizes, example size S & M.