I found mention of Thomas in the archives of Sotheby‘s: The Americana Library of Laird U. Park, Jr.: Lot 98 when they sold copies of the following:
Two separately titled sections (“A Collection of all the Laws of the Province of Pennsylvania: Now in Force” and “An Appendix; Containing a Summary of Such Acts of Assembly”); lightly foxed, browning throughout.
Contemporary calf, morocco label gilt; covers badly scuffed (repaired).
FIRST EDITION. Benjamin Franklin finished the presswork for the present volume in the Spring of 1743 and offered bound copies for sale in late summer, two years after he had originally received the copy from the Pennsylvania Assembly and one year later than the date in the imprint (Miller). References: Miller 288; Evans 5033; Hildeburn 755a-c; Campbell 237a-c Provenance: Andrew Hamilton (signature on title-page) — Thomas Cumpston (signature on title-page). You can read more about Thomas on my website at http://www.cumpston.org.uk/#/thomas-cumpston-philadelphia/4535528472 where you can see a good cameo portrait of him,