British Leyland introduced the Mk3 Mini with several major updates in the last few months of 1969- probably the biggest change was the move to winding windows after the Mk1 and Mk2 'sliders'. A new side trim style was introduced to the cars at the same time, which made use of 3 pairs of, and then one more horizontal parallel line running front to back along both the door and rear quarter panels as part of a wider interior revamp.
A new material was specified by Leyland across its newer car range at the time, so that the facing surfaces in the Mk3 cars were more smoothly grained, and glossier than had previously been the case on the Mini.