Regulations made by the Minister shall impose upon local education authorities the duty of providing milk, meals and other refreshment for pupils in attendance at schools and county colleges maintained by them ; and such regulations shall make provision as to the manner in which and the persons by whom the expense of providing such milk, meals or refreshment is to be defrayed, as to the facilities to be afforded (including any buildings or equipment to be provided) and as to the services to be rendered by managers governors and teachers with respect to the provision of such milk, meals or refreshment, and as to such other consequential matters as the Minister considers expedient, so, however, that such regulations shall not impose upon teachers at any school or college duties upon days on which the school or college is not open for instruction, or duties in respect of meals other than the supervision of pupils, and shall not require the managers or governors of a voluntary school to incur expenditure.