Really lovely white Victorian garden dress with slight dropped waist and gorgeous lace skirt, delicate pleated bodice with a modest high neck, back buttons.  This is pretty wearable too!  Excellent condition with very little discoloration. I have another the same but it has a bit of spotting. (Note- the last pic is of the other one on the dress form, which is not really appropriate as it is an adult form not child, still helps I think ; ) 
Please see pics for measurements.  Probably about a US (womens) size 6, girls size 12 or so.