The Brecknock and Abergavenny Canal was proposed in 1792 to connect the Upper Usk valley to the Monmouthshire Canal at Pontymoile and from there to the sea at Newport. The middle section of the canal, between Gilwern and Talybont and including Llangattock, was cut between 1797 and 1799. The upper section between Talybont and Brecon opened in 1800, both sections being engineered by Thomas Dadford. The lower section between Gilwern and Pontymoile was completed in 1812 and was engineered by William Crosley. The canal was sold to the Monmouthshire Canal Company in 1865, which was later incorporated into the Great Western Railway. The last toll was taken on the canal in 1933 and it was finally abandoned in 1962. The canal, renamed the Monmouthshire and Brecon Canal, has been undergoing restoration since 1964, and is currently used by pleasure craft.

The stop lock lies within the section constructed by Thomas Dadford between 1797 and 1799 and is listed (Ref: 20704).

Source: Cadw listed building database.

A marina was created adjacent to the stop lock, Heron Rest Marina and provides moorings for 50 vessels.

Photographed during aerial reconnaissance by RCAHMW on 21st July 2009.
L. Osborne, 29th June 2012.