Sources

Portalanynlagane 1507 [i.e. Port an Eilein  + Fhinlagan (a saint’s name)]

Port an Eilein: Robertson 2019, p. 403 [also given as ‘Portanellan’]

“Portanellan, for Port an Eilean = Port of the Island; the landing-place from Eilean Finlagan.” Capt. F. W. L. Thomas ‘On Islay Place-Names’ 270

“Portanellan, for Port an Eilein, Port of the Island, i.e., the landing place from the island of Finlagan”  MacNeil, New Guide to Islay, 69