In the UK the only roundnose fitted with an 1100 engine was the "1100 special". So if it has an 1100 it wouldn't be factory.
Looking at the below info from minispares, that car has separate reverse lights, twin stalks, which would indicate a late Mk4 or later. If you can find out if the subframe is a single or twin bolt one that might help too. Of course, anything on it could have been swapped in the past 30 years, so you'd need some better identification like the build plate etc. The wheels and badge on the front would suggest a Rover?
Quote:
Mk3 introduced in November 1969 had wind up windows with internal door hinges except van and pickups. The boot lid lost the original hinged number plate and its recess shape and a large rear colour coded lamp was fitted in its place. Larger rear side windows.
Mk4 introduced in 1976 had a front rubber mounted subframe with single tower bolts and the rear frame had some larger bushes introduced. Twin stalk indicators were introduced with larger foot pedals. From 1977 on the rear indicator lamps had the reverse lights incorporated in them.
http://www.minispares.com/article/Minis ... -mini-typeEdit:
Also the side repeater lights look to be post 1986
http://www.minispares.com/product/Class ... 2592S.aspx