100. If the person who manufactured any material of which an authorised person has taken a sample is not a person to whom part of the sample is required to be sent under regulation 99, that regulation shall have effect as if, for the reference to three parts, there were substituted a reference to four parts, and the authorised person shall send the fourth part to the manufacturer, unless he does not know the manufacturer’s name, or any address of his in the United Kingdom, and is unable, after making reasonable enquiries, to ascertain the name or, as the case may be, any such address, before the expiration of fourteen days from the date when the sample was taken.