A person who is entitled to receive survivor’s benefit under the legislation of Guernsey while he is in Ireland, shall not be credited with a Class 3 contribution in respect of every week during which that benefit is payable to him, but shall be credited, for the purposes of entitlement to retirement pension or death grant, in respect of each year during the whole or part of which such benefit is payable, with a number of Class 3 contributions equal to his spouse’s yearly average of reckonable contributions at the date of her death. If the rate of retirement pension payable to such a person would be less than the rate of survivor’s benefit formerly payable it shall be increased to that of the survivor’s benefit.