The Vintage Wrist Watch Company has dated this piece to the 1900s.
The T-bar is hallmarked for Birmingham 1909, with a maker’s mark for the chain maker Booth & Biggs. The same marks are on the clasp.

The chain comes with a commemorative fob, hallmarked for 1927, depicting a Royal Navy soldier with artillery equipment and possibly a wounded soldier.
The reverse of the fob is engraved Nelson, 1927, T H Field.

HMS Nelson was a British battleship commissioned on August 15, 1927. She was notable for her unique design and served with the Royal Navy during World War II, participating in various operations like the Normandy landings. She was eventually scrapped in 1949 after being used for bombing trials.
The chain measures 32cm long including the T-bar and the clasp. The fob measures 24mm wide, 33mm high excluding the loops. Total weight 43g.
The Vintage Wrist Watch Company has dated this piece to the 1900s.
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