1817 - Percival Norton Johnson establishes business as a London gold assayer;

1822 - premises at 79 Hatton Garden, London

1832-1835 - partnership with George Stokes; known as Johnson and Stokes;

1837 - partnership with W J Cock; known as Johnson and Cock;

1851 - George Matthey joins the company; known as Johnson and Matthey;

1860 - PNJohnson retires; partnership of George Matthey, John Sellon and Edward Matthew; known as Johnson Matthey and Company;

1891 - Johnson, Matthey and Company Limited formed on 11 April

1919 - Johnson, Matthey and Company, Inc formed; branch in Birmingham and Haydn Park Works

1981 - Johnson Matthey Public Limited Company formed 31 July