(1) If the question whether any person was or was not at any time under the influence of intoxicating liquor or if the question as to the presence or the concentration of alcohol in the blood of any person at any time or if a result of a breath analysis is relevant -
...
(c) on a hearing for an offence against section 49(1) of this Act -
then, without affecting the admissibility of any evidence which might be given apart from the provisions of this section, evidence may be given of the concentration of alcohol indicated to be present in the blood of that person by a breath analysing instrument operated by a person authorised to do so by the Chief Commissioner of Police under section 55 and the concentration of alcohol so indicated is, subject to compliance with section 55(4), evidence of the concentration of alcohol present in the blood of that person at the time his or her breath is analysed by the instrument.
(4) Evidence by a person authorised to operate a breath analysing instrument under section 55 -
(a) that an apparatus used by him or her on any occasion under that section was a breath analysing instrument within the meaning of this Part;
(b) that the breath analysing instrument was on that occasion in proper working order and properly operated by him or her;
(c) that, in relation to the breath analysing instrument, all regulations made under this Part with respect to breath analysing instruments were complied with -
is, in the absence of evidence to the contrary, proof of those facts."