Solving crossword puzzles in English, I often have found by jove = aha!
from Urban Dictionary -
In eighteenth and nineteenth century England, it was considered a great offense to say "By God". Instead, men would say "BY Jove".http://jove.askdefine.com/
It was once believed that the Roman god Jupiter (Zeus in Greece) was in charge of cosmic Justice, and in ancient Rome, people swore to Jove in their courts of law, which lead to the common expression "By Jove!"
Aha! as in : By Jove, I think I’ve got it! (don´t you think it makes sense?)http://somethingknew.wordpress.com/2010 ... ve-got-it/
By the way, I have never seen it used in comtemporary movies, novels, news or other means (other than, the crossword puzzle), but then perhaps it´s me.
Anyway, I never say never; since I never have been to the UK or abroad (for that matter