Hi Jean-Marc,
This, though obviously flipped horizontally, should be the Royal Arms of England indeed:
http://en.wikipedia.org/wiki/Royal_Arms_of_England
The heraldic cross with two crossbars -
à double traverse - is generally refererred to as
croix de Lorraine/
croix d'Anjou:
http://fr.wikipedia.org/wiki/Croix_de_Lorraine
Best,
Michael