(1) Section 91 of the Principal Act is hereby amended by the insertion after subsection (5) (inserted by section 16 of the Act of 1981) of the following subsection:
"(6) The weekly rate of invalidity pension shall be increased by £4.20 where the beneficiary has attained the age of 80 years."
(2) Subsection (1) shall come into operation on the 9th day of April, 1992.
(3) Section 91 of the Principal Act is hereby further amended by the substitution for subsection (6) (inserted by subsection (1)) of the following subsection:
"(6) The weekly rate of invalidity pension shall be increased by the amount set out in column (8) of Part I of the Second Schedule where the beneficiary has attained the age of 80 years."
(4) Subsection (3) shall come into operation on the 30th day of July, 1992.