Its going to be a pond. I picked it up yesterday along with a load of old vintage stone planters. The sink was the heaviest, being an extra large one. It nearly killed me even though I had a sack Barrow, lifting it onto the van was challenging. My wife claimed it as hers and has wanted a pond feature for a while.
I sourced a liner and a couple of pond plants while in Coventry yesterday. The liner will be cut to size as was way too big. Pebbles to cover the bottom, some rocks in the corners to enable creatures to get in and out. I will get a solar powered aerator to keep the water clean and some pond weed for the same reason. Then just wait and observe what happens. A friend of my wifes has the same set up and a frog visited her pond recently.
Siting the sink was a little bit of a challenge although easily overcome. The underside of the sink where the waste pipe would be fixed has a bulbous protruding area which means the sink wont sit level on a level surface, if it was on mud the protrudence could be absorbed. So I slid a spare paving slab under the opposite end to level it up.
This project will keep my wife occupied for a while, until she wants new additions to the pond of course !!