The Romans called it Londinium, in Gaelic it became Lundrain. This could explain that in English the R not being pronounced, disappeared and gave something like Lundain and then London while on the French side of the channel, where the R is more significant than following diphtongs it turned into Lundre, got an S to finish the word and ended up being Londres.
Since we are on the subject of common historical backgrounds, does anybody know why the English Coat of Arms (the one that is on the Queen's carriage and everywhere else) shows:
"Dieu et mon Droit
Hon y soit qui mal y pense"
(that should in fact read "Honnit soit qui mal y pense)
?
It is actually a rather crunchy story but I know only the crunchy bit, about the garter...
Courtesy of: http://www.fleurdelis.com/royal.htm