Shell Grotto

In the 18th Century, garden features were designed not only as objects of beauty but also to stimulate the deepest emotions.

These feelings were indulged to the full in the fashion for building grottos – rough hewn structures which suggested mysterious journeys into the earth, where shadow and gloom were relieved only by the sparkle of minerals and ancient shells.

The cylindrical grotto in Pontypool Park is built from local sandstone with a conical roof, but its plain exterior gives no clue as to what lies within.

Set in the floor are bones and teeth of animals set in patterns to form arcs and circles, stars, hearts and diamonds. The walls are mostly bare stone, with calcite crystals and the remains of moss, trees and other vegetation in places. The two remaining windows contain coloured glass.

The ceiling is the glory of the Grotto. It is fan vaulted, six fans rising from six pillars, and in the centre of the dome large artificial stalactites hand down. The pillars and ceiling are covered with thousands of shells interspersed with minerals and real stalactites removed from local caves.


Considered to be the best surviving grotto in Wales, the shell grotto in Pontypool Park stands on a ridge 700ft above sea level.

Although the grotto was constructed as a summerhouse for the Hanbury family of iron masters who owned Pontypool Park, its precise age is uncertain. It is however, thought that the basic structure was built for John Hanbury sometime before his death in 1784.

In the early 1800s John’s son Capel Hanbury Leigh, occupied much of him time adding to and improving his house and grounds in the park. Capel’s wife Molly, a wealthy widow from the Knoll near Neath, is credited with inspiring many of these improvements including the spectacular shell decoration inside the grotto.

There remains speculation as to who actually constructed the shell interior. However, while she lived at the Knoll, Molly was known to have a shell collection and her family subscribed to illustrated 18th Century books on grottos. It is possible therefore, that following the lead of other wealthy ladies, Molly spent many painstaking hours collecting the shells and arranging them in Pontypool grotto herself.

Another possibility is that the decoration was the work of an early job creation scheme. The Monmouthshire Merlin reported that during the harsh winter of 1829 – 30, Capel Hanbury Leigh had given employment in his grounds to about 85 men, women and children.

The grotto was used by the Hanbury family as a venue for picnics on nearby shoots until the early 20th Century. One event of note occurred around 1882 when the Prince of Wales (later Edward VII), was a member of a shooting party picnicking by the grotto. All was well until the two jeroboams of champagne carried to the grotto (each equivalent to four normal bottles), were opened and found to be corked!


During the winter of 1991/92 sections of The Grotto roof collapsed, raising questions over the future of the hilltop Grotto.

The Grotto had been closed to the general public for almost 20 years. The condition of the Grotto was poor in the 1970’s but by the1990’s lay in a state of sad neglect and disrepair. The roof was badly misshapen and letting in water, not to speak of the vandals, and both had caused huge areas of damage to the decorated interior.

Clearly without action the Grotto had no future. Initial research into the cost of restoration began. The costings were alarmingly high and the quest for external financial assistance to match Council monies commenced.

The roof of the Grotto was patched in January 1992 but within months further damage had occurred from the differing elements.

Fortunately, substantial monies were secured from Cadw and the European Regional Development Fund during 1992/93.

Restoration of the exterior took place in 1993/4 taking 8 months to complete and included:

  • Rebuilding of the stone chimney
  • Replacement of roof timbers
  • Repairs to damaged stone work
  • Replacement door, windows and shutters

Works to the exterior were finally completed in the summer of 1994 at a cost of £75,000. This sensitive work was undertaken by Nick Barter, a builder from Monmouth, with specialist advice from Davies Sutton Architecture.

The exterior of the Grotto was now fully restored, wind and watertight, but the magnificent shell interior remained in a sorry state of disrepair. Indeed, despite efforts the shell ceiling and pillars had suffered during the course of the major repairs to the roof and required major restoration to the vaulted ceilings, pillars, walls and floor.

During 1995 the campaign began again to raise funds to match the Council’s resources. Finance was secured from Cadw and the Grotto hit the jackpot and received one of the first Heritage Lottery grants in Wales.

In 1996 – the restoration of the shell interior commenced. A specialist team of conservators (St Blaise Ltd) were chosen with expertise in the restoration of intricate plaster and shell work. The repairs to the ceiling, pillars, walls and floors was a slow and delicate process extending over a period of 4 months.

A detailed photographic record had been taken of the shell interior some years earlier and this was valuable in ensuring that the repairs were true to character. Many of the shells and minerals that had been dislodged had been stored away and these, together with replacement material, were used in the careful restoration process.

The restoration of one of the finest Shell Grottoes in Wales was completed in December 1996, enabling residents and visitors to Pontypool to once again visit this magnificent hilltop Grotto and enjoy the splendour of the shell interior and the panoramic views.

The placing of the shells and the reinstatement of new roof work was an art in itself and was very much left to the skill of the conservator. To create patterns which worked well into the existing designs, and to entwine the ivy in between the minerals and round the door post so they looked as if it had grown and invaded the building was a great challenge but ultimately extremely successful.

The root work around walls and ceiling was riddled with worm. To stabilise these almost hollow structures a resin and solvent mixture was painstakingly injected into the holes with a hypodermic needle. When the solvent evaporated the resin hardened making the whole root solid.

The rustic chairs were carefully restored by piecing in new segments which were missing, repairing broken sections, and scraping back layers of modern paint. The chairs had originally been painted, the dull green colour being analysed under the microscope and dated to the middle 19th Century. With the new pieces of wood needing to be painted, it was decided to repaint all chairs in a specially mixed colour to match the original.


Access to the Shell Grotto is by walking only and involves steep climbs over uneven ground and is unsuitable for the less abled and young children.

Last Modified: 05/12/2018
For more information contact:

Pontypool Park

Tel: 01495 766754

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