Changes made by Social Security (Severe Disablement Allowance) 1984
S.I. 1984/1303
Made to Social Security (Sickness and Invalidity Benefit and Non-Contributory Invalidity Pension) 1983
1 change. All changes made by Social Security (Severe Disablement Allowance) 1984
From legislation.gov.uk's record of changes, the official one: see it there.