This information has been updated with many thanks to Miles Harrison, who has recently published a new book "Exeter and West Country silver 1700-1900".  This is an extremely comprehensive book and can be bought directly from Miles.

William Pearce was actually a Plymouth maker.  His first record of work sent for assay was in 1774.  He was last mentioned on 2nd February 1797.

There are some curious anomolies regarding the dating of William Pearce tongs.  We have records of him having tongs assayed between 1780 and 1784. Unfortunately we don't have any records for the period between 1784 and 1794. He does not appear to have sent in any tongs for assay from 1794 onwards. This means that in theory his tongs must all be dated between 1780 and 1793. This does not tie in with the assay office records and apparent date of some of the tongs.

We also see quite a variety of different maker's marks for William Pearce.