Changes to Social Security (Miscellaneous Amendments and Transitional Provisions) 1975
S.I. 1975/566
Made by Social Security (Widow's Benefit and Retirement Pensions) 1979
1 change. All changes to Social Security (Miscellaneous Amendments and Transitional Provisions) 1975
From legislation.gov.uk's record of changes, the official one: see it there.