If the holder of a justices' licence—
(a)knowingly suffers to remain on the licensed premises any constable during any part of the time appointed for the constable's being on duty, except for the purpose of the execution of the constable's duty, or
(b)supplies any liquor or refreshment, whether by way of gift or sale, to any constable on duty except by authority of a superior officer of the constable, or
(c)bribes or attempts to bribe any constable,
he shall be liable, on a first conviction to a fine not exceeding ten pounds, and on a subsequent conviction to a fine not exceeding twenty pounds.