Where a person who has attained pensionable age is in receipt of or entitled to, a widow's (contributory) pension, widower's (contributory) pension or old age (contributory) pension or is a person in respect of whom an increase of old age (contributory) pension is payable by virtue of section 112 (1) and would but for section 160 be qualified for the receipt of an old age (non-contributory) pension -
(a) the person may, notwithstanding anything contained in section 160, be paid the old age (non-contributory) pension for any period during which the rate of pension payable would be greater than the rate of widow's (contributory) pension, widower's (contributory) pension, old age (contributory) pension or the increase thereof, as the case may be, payable, and
(b) in any case where the old age (non-contributory) pension is so paid, entitlement to widow's (contributory) pension, widower's (contributory) pension, old age (contributory) pension or the increase thereof, as the case may be