Cast iron post on the W bank of the upper pond (nprn 91628) at Garnddyrys Ironworks (nprn 34137). The works was in operation c1817-61. The post is later than 1836, when the Blaenavon Company was formed, and was probably cast for use as a boundary marker.

The post is 0.7m high, tapering with a rounded top, and has 'B Co' in raised letters. (See also nprn 270039, for a similar post found S of Blaenavon on Coity Mountain).
R Hayman, Hayman & Horton, 26/11/2003