On the trial of a person charged with any offence relating to any seal or stamp used for the purposes of the public revenue, or of the post office, in any part of the Sovereign’s dominions or in any foreign state, a dispatch from 1 of the Sovereign’s Principal Secretaries of State, transmitting to the Governor any stamp, mark, or impression, and stating it to be a genuine stamp, mark, or impression, of a die, plate, or other instrument, provided, made, or used, by or under the direction of the proper authority of the country in question for the purpose of expressing or denoting any stamp duty or postal charge, is admissible as evidence of the facts stated in the dispatch; and the stamp, mark, or impression, so transmitted may be used by the court and jury and by witnesses for the purposes of comparison.