WRITING & SCHOOL SLATE MANUFACTURERS

1856

Roberts, Griffiths & Co. - Glanmorfa Slate Works

1858

Roberts, Griffiths & Co. - Glanmorfa Slate Works

1859

Roberts, Griffiths & Co. - Glanmorfa Slate Works

1868

Roberts, Griffiths & Co. - Glanmorfa Slate Works

1874

Roberts, Griffiths & Co. - Glanmorva Slate Works
Williams & Co. (Dorothea Writing Slate Works) - Slate Quay

1876

Roberts, Griffith & Co. - Glanmorva Slate Works
Williams & Co. (Dorothea Writing Slate Works) - Slate Quay

1878

(Cassey)
Roberts, Griffith & Co. - Glanmorva Slate Works
Williams & Co. (Dorothea Writing Slate Works) - Slate Quay

1880

Griffiths & Co. - Glanmorva Slate Works
John H. Williams - Slate Quay (& Dorothea Slate Works, Llanllyfni)

1885

Griffiths & Co. - Morfa Slate Works

1889

Morris Roberts - Glandwr
Williams, Griffiths & Co. - Glanmorfa

1901

Morris Roberts - Glandwr
Williams, Griffiths & Co. - Glanmorfa

1903

Morris Roberts - Glandwr
Williams, Griffiths & Co. - Glanmorfa

1912

(TDL)
Williams, Griffiths & Co. - Glanmorfa

1917

Williams, Griffiths & Co. - Glanmorfa

1918

Williams, Griffiths & Co. - Glanmorfa

1927

Williams, Griffiths & Co. - Glanmorfa

1928

Williams, Griffiths & Co. - Glanmorfa

1936

(Bennett)
Glanmorfa Slate Works Co.