This is an amazing dress!
Original 1968 Biba wool maxi dress. 
Long sleeve design with simple cuffs, large oversized funnel neckline design with darted bust and A-line cut to the body. No opening simple pull over style with original woven label in the neckline. 
Iconic pieces this does have some flaws, popped seams in a couple of places like the bust dart and shoulder, it has some holes in places and markings all over. This said, with a gentle dry clean and some hand darning this piece would be Amazing again but can easily be worn with little work. 
Measures when laid flat 
Armpit to armpit - 18"
Waist - 16"
Length - 52"
Sleeve length - 22"