(1) In the case of beer subject to alcohol products tax at the rate for beer exceeding 2.8% vol, a relief of half the amount of alcohol products tax paid on such beer shall, subject to subsection (3) and to such conditions as the Commissioners may prescribe or otherwise impose, be granted on a quantity of beer, not exceeding 30,000 hectolitres in a calendar year, brewed in a brewery -

(a) in which the quantity of beer brewed in the previous year has not exceeded 75,000 hectolitres,

(b) which is legally and economically independent of any other brewery,

(c) the premises of which are situated physically apart from those of any other brewery, and

(d) in which less than 50 per cent of the beer brewed in the previous calendar year has been brewed under a licence, franchise or contract arrangement for another brewery.