Castle built his own grotto on one and a half acres of land near Moxon Street (Grotto Passage stands on the original site) and people flocked to see his intricate shell designs housed in tents and sheds. In 1748 one newspaper reported, “At Marybon is to be seen, Castle’s great and inimitable GROTTO, or SHELL-WORK, so much admired by the Curious”.
The Grotto also offered meals and various entertainment and even attracted members of the royal family – leading Castle to call it the ‘Royal Grotto’ and to raise the entrance fee from one shilling to half a crown. According to one 19th-century London historian, it was an ““Exhibition of Shell-work, called the Great Grotto, the property of one John Castles, who died in 1757; the ingenuity of this artist appears to have been duly appreciated by the Public, his Exhibition have been a celebrated place of fashionable resort.”
Castle died in 1757 and the Grotto was never the same afterwards; it closed finally in 1759 and was built over, but at least its name lives on in the passage and also on the name of a school carved into a wall in the passage: The Grotto Ragged and Industrial Schools.
The school was established in 1845, part of the 19th-century movement of ragged schools, charitable organisations dedicated to the free education of destitute children. A report on the school paints a vivid portrait of what the area was like in the Victorian age, pointing a particularly disapproving finger at the oldest profession.
“The district selected by the founders for their beneficent efforts is notoriously one of the most debased spots of London. The nest of courts midst which it is planted form an oblong square, so flanked by the residences of the aristocracy that a stone’s- throw suffices to divide the homes of penury from the halls of luxury. In no part of London does the “great social evil,” as it has been aptly termed, form a more prominent feature—the only distinction being that, whilst the reveller of the Haymarket flaunts in silk and satin, with brandied-eye and rouge-cheek, the wretched tenants of this place are too poor to disguise their vice, or too degraded to seek to hide their occupation, Jezebel like, by paint.”