Throughout all the building changes and additions, mostly a response to rising student numbers, the function of the Union remained much the same - to serve the multifarious needs of what constitutes a small city of students and to a lesser extent staff and graduates. By the 1950s, the Union was no longer meeting the needs the latter two groups. In 1952 the staff retreated to their own Club (University House) and the Graduate Union (eventually set up in Graduate House in Leicester Street - opened 1962) was constituted as a separate entity. The Union became a centre for student life and action only.
By the 1965 the Union facilities were once again manifestly inadequate and most of the remnants of the old Museum building were demolished to allow for expansion.
In the 1970s there were further extensions to the west and the interior around the cafeteria completely remodelled. In 1988 an exterior staircase was added at the west end. For all these changes, the building remains symmetrical around the axis of the Old National Museum building.