1839 EL to Waterford, abuse of Free Frank

1839 Entire Letter from Falmouth to Waterford, apparently carried privately (by ship?) to Belfast, carried from there under the Free Frank system and signed "Donegall" (Earl of Donegal), with a very fine crowned FREE of Dublin (F/K 128) in red and with arrival cds of Waterford for the next day.
A very rare usage showing abuse of the Free Frank system to evade postage on commercial correspondence.