Article: After the establishment of Hampshire County Council, following the act in 1888, Southampton became a county borough within the county of Hampshire, which meant that it had many features of a county, but governance was now shared between the Corporation in Southampton and the new county council. There is a great source of confusion in the fact that the ancient shire county, along with its associated assizes, was known as the County of Southampton or Southamptonshire. This was officially changed to Hampshire in 1959 although the county had been commonly known as Hampshire or Hantscire for centuries. Southampton became a non-metropolitan district in 1974.

Question: What designation was Southampton given in 1974?
non-metropolitan district