6% Exchange Surcharge. 1842 Lampeter, GB (Apr 2) to Wellington Square, UC via Liverpool, Boston, USA, Queenston, UC via Cunard “Britannia”, rated 1/- Stg packet rate via US = 27c US (2c ship+25c postage to border), converts to 1/4 1/2 Cy plys 7d Cy from the border to Guelp, for a total of 1/11 1/2d due, plus 1d being the 6% Exchange Surcharge.
The 6% Exchange Surcharge was added to compensate the border post masters collecting and remitting postage to the USA. The period of use was March 1, 1832 until May 16, 1842, a very short period.