18.(1) There shall be charged, levied and paid to the Government out of all monies paid or agreed to be paid by a licensed bookmaker to a backer in consequence of the winning by the backer of a bet made in an enclosure set apart under the provisions of the ¹[* * *] Public Gambling Act, 1867, as amended from time to time, on any race, a tax on backer hereinafter referred to as the betting tax, amounting to twenty per cent. of all such monies. (2) The betting tax shall be deducted or collected by the licensed bookmaker from such monies at the time when the money is paid to the backer, or in the case of credit bets at such time as may be prescribed, and shall be deemed to have been paid by the backer on account of the tax, and shall be retained by the licensed bookmaker on behalf of the Government.