Well actually I have been partially wrong all this time
if in london they count 79 sunsets and 76 moonsets Phileas Fogg in his travel would have counted one more of each
All this time I have been using a model in which Earth rotates at half the speed the moon takes for a full rotation around earth
In this way the Sun and the Mon have different apparent sense in the sky so my idea would work since Fogg would have counted one more Sun and one less Moon than in Greenwhich in this case
Anyway I still think ancient people could obtain longitude easy what im still figuring out
edit:
The reason we see always the same face of the moon is tidal lock
http://en.wikipedia.org/wiki/Tidal_locking
This is due to the center of gravity and center of mass of the Moon being in different places since gravity varies with the distance SQUARED