This birdbath has to be the most basic design, taking a Purbeck stone/rock and chiseling out a bowl, placing it on a plinth of Purbeck stone with levelled-off top and bottom beds and finally placing it on a slab of natural faced Portland stone with a flat panel worked to accommodate the bottom mould or shape of the plinth.
Purbeck stone has a variety of naturally occuring bed heights ranging from just an inch or two up to feet. This makes it an ideal flooring and paving material if two to four inch thickness is required or for steps nine or so inches are required. It also has the property of being watertight so ideal for external work, including a birdbath