In the first half othe the 18th century there are a number of gaps in the timeline where no Bath handstamp are currently known. A 26x8 mm handstamp was known from 1738 and 1739, a 26x12 mm handstamp is recorded in the British County Catalogue from 1742, and a 28x7 mm handstamp is known from 1750-1757.
The entire below is dated 20th January 1745 inside with a somewhat degraded handstamp that matches the 26x8 mm handstamp from 1738-1739 (checked by overlaying scans of the handstamps).
I have not seen an example of the 26x12 mm handstamp from 1742 that is recorded in the BCC.