Not all early English-made precious metal pens and pencils bear hallmarks.  Those produced by Sampson Mordan & Co. can be approximately dated, however, by the following markings:

S MORDAN & CO.S PATENT    1824 - 1830
S MORDAN & CO MAKERS & PATENTEES    1830 - 1845
S MORDAN & CO MAKERS    1845 - 1852
S MORDAN & CO    1853 - c. 1941