Penrhyn Quarries Ltd.
Penrhyn Castle, Gwynedd (Accredited Museum)
Crown Slate
National Trust Museum of Childhood (Accredited Museum)
Erddig, Wrexham (Accredited Museum)
Calke Abbey, Derbyshire (Accredited Museum)
Betts
G. E. Magnus
Penrhyn Slate
Mr Straw's House, Nottinghamshire (Accredited Museum)
Killerton, Devon (Accredited Museum)
Tyntesfield, North Somerset
Snowshill Manor and Garden, Gloucestershire (Accredited Museum)
Dunster Castle, Somerset (Accredited Museum)
Rufford Old Hall, Lancashire (Accredited Museum)
Japy Freres
