This little roller bearing goes inside the end of the 1st motion shaft on minis with 14mm mainshaft which it sits on.
This bearing was previously part number 88G409 and a true Rover replacement, but if you have earlier A type gears with the fixed sleeve type bearing 22G314, they have been obsolete from the manufacturer for many years. Unless you can find a new old stock item never try and get this bearing out, as it usually breaks up