Notwithstanding any other provisions of this chapter any member of the policemen’s retirement system who makes application for benefits under this chapter and who was at the time a member of an insurance or hospitalization group plan for which payroll deductions are authorized, may request that the monthly premium for such service be deducted from the monthly retirement benefit which he is to receive, and in such case said deduction shall be made from the sums due the member. Provided, further, that deductions from retirement benefits shall be made, if requested by retired policemen receiving such benefits, who transfer an existing direct pay membership or subscribe as a new member for such plan, if permitted by regulations of such plan.