The former Oil Rig construction site lay empty for many years then in 1988 the site was leased from the Hunterston Development Company to Costan Taylor Woodrow to construct a Trident Submarine Dry Dock for the neighbouring Coulport Navel Base up the Clyde.
They decided that the site was too small and reclaimed more land for the sea, this was proposed as storage for the various parts and materials so they could construct it on site before lifting it into the main structure, but it was found out afterwads that the area they reclaimed was never needed and was a waste of time, effort and cost.
The two images below show the site before and after the additional reclaim. The image on the left is the site shortly after completion in 1976 and the image on the right is taken in 1996 after the site was empty again. The new part that was reclaimed can be seen with the yellow dots.