This is a plaque to the Cumberland Basin Stabilisation Works, completed in 1991, about which I can find virtually nothing on the internet. The face is too crumbled to read all the words, but I seem to remember that it's a lot more legible at certain times of year/day when the sunlight slants across its face. I'll keep an eye out for a better photo opportunity.
In the meantime, there's a picture of this entire area being resurfaced while the basin is drained and dredged on this selection of 1991 photos on the Evening Post site, which I'm assuming might have been part of this project.
GPS Coordinates:
51.44762, -2.62057
Location: Cumberland Basin