The Grotto at Painshill, Cobham, Surrey

Of all the ideas which percolated to England from Italy – sometimes via France – the grotto is one of the most surprising. The earliest examples were often a room within the dwelling – such as at Woburn Abbey and Skipton Castle and were mostly decorated with shells. By the 18th century they were becoming more elaborate – probably inspired by examples seen on the Grand Tour such as in the Boboli Gardens in Florence.

Charles Hamilton laid out his garden at Painshill between 1738 and 1773, when he had to sell to pay off his debts. The main phase of construction of the garden buildings started in the 1750s and in the 1760s Hamilton entrusted the construction of the grotto to Joseph Lane and his son Josiah of Tisbury. It is on an artificial island and has a brick structure covered by spongestone – the bricks were made on the estate – with lathe and plaster formwork for the elaborate arrangement of stalactites and stalagmites within.

Hamilton seems to have followed Leonardo da Vinci’s advice that a grotto should evoke fear and desire. The entrance is down a dark passage with only a few feet lit up from outside and is certainly disconcerting, but the desire to see what is concealed draws the visitor in. The inner chamber is a fantastic cavern decorated with calcite, gypsum, amethyst and ironstone. Carefully positioned gaps allow light in and the reflection of the water outside makes the mineral shimmer. Water from the lake – now pumped – runs down the walls and back into the lake.

It cost £8,000 to create the grotto and for a time the grotto making business thrived but sadly they went out of fashion and there is a record of Josiah Lane in the workhouse. The roof collapsed in 1946 and the grotto was in a sorry state when the Painshill Park Trust started renovations of the whole landscape in 1981. The Heritage Lottery Fund and other donations raised the £747,000 needed for the restoration of the grotto and it is now one of the many attractions of this important landscape garden.