of 172 Blackfriars Road, London
1822 The mechanical pencil was invented by Sampson Mordan and Gabriel Riddle - the earliest Mordan pencils are hallmarked SMGR. Note: There is an opinion that the propelling pencil was invented by John Isaac Hawkins with Sampson Mordan and that Gabriel Riddle was a manufacturer.
1837 Partnership dissolved. '...Partnership heretofore subsisting between Sampson Mordan and Gabriel Riddle, under the firm of S. Mordan and Co., (by virtue of an indenture made in October 1823), and carrying on business as Mechanists and Manufacturers of Patent and other articles, at No. 22, Castle street, Finsbury, London, was, on the 20th of December last, dissolved, by the expiration of the term limited in the said indenture...'
1837 Of 25 Paternoster Row
1841 Manufacturer of superior articles including pens, pencils, ink holders, and locks on the Bramah and Barron patent principle
Sources of Information
-  Gazette Issue 19458 published on the 17 January 1837. Page 16 of 28
- Perry’s Bankrupt Gazette - Saturday 16 March 1839
- Post Office London Directory, 1841