Gideon Parkman was born 11 April 1777 in Abington, MA the son of Daniel & Hannah (House) Parkman and the grandson of Gideon & Mary (Vining) Parkman. Gideon married Martha McClure/McLure.
Before coming to Palmyra, Somerset,ME he lived in what is now Skowhegan, Somerset, Maine. I have checked the Parkman genealogy (1999, Kenneth Lary, Jr.) and I find only one mention of anyone named Leach/Leech. According to the history portion of Palmyra in the "East Somerset County Register, 1911-1912" "Palmyra was originally purchased from the State of Massachusetts by Mr. Barnard of New Hampshire and afterward sold by him to Dr.John Warren of Boston for 12 1/2 cents an acre." Perhaps your Leach ancestor was a land speculator. Did the deed say how much was paid per acre for the land? You might try posting a query on the Somerset Co., Maine Message Board.