# Gun Barrel Proof Act 1978, Paragraph 4


(1) Subject to sub-paragraph (2) below, in any proceedings for an offence under the Act of 1868 it shall be for the defendant or, in Scotland, the accused to show that any exemption under this Schedule is applicable to the case.
(2) Subject to sub-paragraph (3) below, a person shall not be convicted of an offence under the Act of 1868 by virtue of any withdrawal of exemption under paragraph 2(2) above unless it is shown that he knew at the time when the offence is alleged to have been committed that the exemption had been withdrawn.
(3) Sub-paragraph (2) above does not apply in any case where the defendant or, in Scotland, the accused was at the time when the offence is alleged to have been committed a gun maker or gun barrel maker, or a maker of or dealer in small arms or barrels, or in any parts for small arms or barrels.
(4) For the purposes of any proceedings for an offence under the Act of 1868 the former register kept by the Proof Master of either of the Two Companies shall be conclusive evidence of the contents of that register as it had effect immediately before the passing of this Act, without production of any original document received from any consular authority or agent, and without proof of any other fact in verification of that register.

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Source: https://www.legislation.gov.uk/ukpga/1978/9/schedule/2/paragraph/4 (the official version)
Page: https://openlegislation.uk/gun-barrel-proof-act-1978/schedule-2/paragraph-4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.