4.—(1) Subject to paragraph (2) of this Regulation, where any premises or plant in existence or under construction immediately before the coming into operation of these Regulations complied with the Factories Act 1961 as then in force, then those premises or that plant shall be deemed to comply with that Act as amended by these Regulations.
(2) Notwithstanding paragraph (1) of this Regulation, sections 3(2), 68(4) and (8) of, and the First Schedule to, the Factories Act 1961 as amended by these Regulations shall apply in all relevant workrooms whether or not in existence or under construction immediately before the coming into operation of these Regulations, but nothing in this paragraph shall prevent the use of thermometers graduated in degrees Fahrenheit in workrooms under construction or in existence immediately before the coming into operation of these Regulations if such thermometers are provided with suitable conversion tables to convert their readings to degrees Celsius.