I have recently found the will of Nicholas Fontaine probated in London 1583. This Nicholas Fontaine may be the son of Jean de la Fontaine (ca.1485 St. Lô, Manche, Normandie - 1584 Manche, Normandie) and Nicole d'Arguillieres (ca. 1500 France -1584 France). If so, his birth and death dates are most likely: born bet. 1519 and 1530 in Normandie, and died after 26 January 1583 (when the will was probated) in England.
His siblings would then probably be: François, René, Michel, Philippe, Madeleine, Marguerite, Jeanne, Guillaume, Marie, Artus, Georges and an older brother whose name is unknown - all born in Normandie.
Other people mentioned in the will: Marguerite, first wife; Adriene Heindreig, second wife; Nicholas Fontaine, son; Mary Fontaine, daughter; John Lyonblon, son-in-law; Denys Le Blancq, notary public; and Godefroy de Dagnourte (relationship to testator unreadable, possibly business partner).