With the introduction of the rear seat squab frame in 1960, the rear seat foams were changed from a horsehair pad to this flat squab foam. This modern day specification foam replacement is placed over the rear seat frame and then the edges are turned around the frame and glued. It was used from 1960 until the end of MKI production where the foams had additional foam built onto them to give a more defined shape. With the reintroduction of the Mini Cooper in the 1990's they again adopted this flat squab foam.
We recommend the fitting of new foams when fitting new seat covers as the covers are often glued to the foam which can cause damage to the foam when removing, however as the rear seats are less used than the fronts we recommend using your discretion on this. Our sales team will be happy to advise.