18. The requirements referred to in regulation 13(1)(a) shall, in the case of such a student, include—
(a)where at the beginning of the first year of his course he was aged 26 years, the sum of £280;
(b)where he was so aged 27 years, the sum of £500;
(c)where he was so aged 28 years, the sum of £750;
(d)where he was so aged 29 or more years, the sum of £980.