4. Where the number, which appears to the funding authority, to be the number of registered pupils in a particular age band at the school on 19th January 1995, differs from the number of registered pupils of that particular age band which it was estimated, for the purposes of determining the amount of that school’s annual maintenance grant or budget share in the preceding financial year, would be at the school on that date then the funding authority shall determine an amount in respect of such category of pupils by—
(a)subtracting that estimated number from that actual number of registered pupils and multiplying the resulting amount by the amount specified in relation to the authority in whichever is the appropriate of column 2, 3, 4 or 5 in the Table in Schedule 5 in relation to that age band and by the proportion of that preceding year in respect of which pupil numbers were estimated (expressed as a fraction in the entry for the authority in column 1 in the Table in Schedule 5);
(b)multiplying the sum of the numbers calculated in accordance with sub-paragraph (a) above by the age band 3 unit cost for the authority in column 6 in the Table in Schedule 5; and
(c)subtracting from the amount calculated in accordance with sub-paragraph (b) above any amount previously made available for the purposes of the school because of an increase in the number of registered pupils at the school.