In the case of a person who is in receipt of blind pension under Chapter 5 of this Part, widow's (non-contributory) pension, widower's (non-contributory) pension or surviving civil partner's (non-contributory) pension under Chapter 6 of this Part, one-parent family payment under Chapter 7 of this Part, a payment referred to in paragraph (b) or (c) of the definition of "relevant payment" in section 178, disability allowance under Chapter 10 of this Part or farm assist under Chapter 11 of this Part, immediately before becoming entitled to State pension (non-contributory), the weekly rate of pension payable shall be the greater of -

(a) an amount equal to the rate of blind pension which was payable in accordance with sections 161B, 161C and 161D immediately before becoming entitled to State pension (non-contributory) and the rate payable in accordance with sections 156, 157 and 158, or

(b) an amount equal to the rate of widow's (non-contributory) pension, widower's (non-contributory) pension or surviving civil partner's (non-contributory) pension which was payable in accordance with section 164 immediately before becoming entitled to State pension (non-contributory) and the rate payable in accordance with sections 156, 157 and 158, or