The annual amount of any periodical payment made to any person by virtue of his past membership of the House of Commons shall not exceed £2,451 or such sum as, in the opinion of the Trustees, will bring his income up to £4,512 per annum, whichever is the less:
Provided that if, having regard to length of service and need, the Trustees think fit, they may make a larger payment not exceeding £4,728 or such sum as, in their opinion, will bring his income up to £6,789 per annum, whichever is the less