Scottish Additional Halfpenny Mail Tax marks.  These marks were introduced in 1813 following the partial repeal of an Act of Parliament which had granted exemption of toll charges for mail coaches. With mail coaches being charged tolls in Scotland the Post Office responded by levying an extra halfpenny on all letters carried by mail coach in Scotland.  The tax was abolished on 5th December 1839 with the introduction of Uniform Fourpenny Postage.