For the purposes of a prosecution of the parent of a child for an offence against section thirty-seven or section thirty-nine of the principal Act (which relate respectively to failure to comply with a school attendance order and to failure of a child to attend regularly at school), in so far as the child's having been of compulsory school age at any time is material, the child shall be presumed to have been of compulsory school age at that time unless the parent proves the contrary.

An obligation under the preceding subsection to presume a child to have been of compulsory school age at any time shall be in substitution, so far as regards the purposes for which that presumption is required to be made, for the power conferred on the court by subsection (1) of section ninety-five of the principal Act (which is a power to presume a person to be under, of, or over, an age alleged by the person by whom any proceedings under the principal Act are brought on his satisfying the court that, having used all reasonable diligence to obtain evidence as to the age of that person, he has been unable to do so).