Joan Stevens noted in Vol 1 of Old Jersey Houses that La Fosse was the only house in Jersey with six granite fireplaces surviving in the 1980s. Unlike virtually every other Jersey house surviving from the 17th century and earlier, the front door faces north rather than south.
The house passed by marriage from the Gallie family to the Larbalestiers, and in the 19th century it was owned by the Amy family. The northern arch bears the date 1668 and a shield with the initials PLB and AG, for Philippe Larbalestier and Andree Gallie, daughter of Clement, Constable of Trinity from 1652 to 1660.
Another stone, removed to the Jersey Museum, is inscribed 1686 MLB MCB, which Stevens suggests indicates a son of Philippe with the initial M, married to a Cabot. The Jersey Datestone Register confirms the marriage of Philippe's twin son Michel, born in 1642, to Marie Cabot in 1671.
Stevens says that when Philippe Larbalestier wanted to enlarge the house which he and his wife had inherited, he was limited by the slope of the land and added a wing running east-west, with its entry on the north. The enclosed stairway on the south is one of only two straight, enclosed stairways found in Jersey houses of this era, the other being Coutanche Farm in Trinity.