According to Wikipedia, "A design mark with an eagle and a ribbon and the words "Economical, Brilliant" was the first registered trademark, filed [in the USA] by the Averill Chemical Paint Company on August 30, 1870 under the Trademark Act of 1870. However ... the U.S. Supreme Court held the 1870 Act to be unconstitutional. The oldest U.S. registered trademark still in use is ... a depiction of the Biblical figure Samson wrestling a lion, registered in the United States on May 27, 1884 by the J.P. Tolman Company (now Samson Rope Technologies, Inc.), a rope–making company."
So it would appear that although the Bass red triangle was the UK's first trademark, it wasn't the world's first; but it was probably the first one that was used without being declared legally unusable. It would also appear to be the oldest one that's still in use.
© Haydn Thompson 2017