My first thoughts were the lower-case f indicates a date of 1928. However, my research suggests that for this date and assay office, the "f" should appear within a shape which is a rectangle but with an irregular "scalloped" lower edge and sharp right-angle upper corners.
Can anyone help please to clarify this matter and/or comment on whether my proposed dating is correct. Also, can anyone advise what the mark below the serial number relates to. The mark apears to be a squat-shaped hammer. Thanks for your assistance.
![Image](http://e.imagehost.org/t/0041/Bensonwatch.jpg)
![Image](http://e.imagehost.org/t/0883/Bensonwatchhallmark.jpg)
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