This is a totally unique and so hard to find, believed 1980's, vintage ANOKHI Indian block print maxi dress from Jaipur India.Think true artisan, bohemian, craft, hippie, festivals. 
Has a fixed but loose at lower edge over bib front which then ties loosely at the back
Wonderful block print pattern which naturally will have colour variants and some irregular outlines- possibly some natural burring of lines. 
The material is 100% cotton but it is a heavier weave cotton. At first i thought it must be a linen blend.  
Two very small repairs- were small cuts in material and have been repaired. please see last photo.These are situated either side of front right side seam very low down. No one will see them
The label states 34 which in Anokhi sizing would be a UK 6 BUT please see my measurements below
length from shoulder to lower edge 60ins
pit to pit, ie, side seam to side seam under arm 18ins
length of inner sleeve 18ins
Length of outer sleeve 25ins