What song was patrik singing

Rating: Null/10 (17 January 2007)

When Theo and Kee get help from the Russians and are on their way to get a boat out of Bexhill, the Fish catch up to them and go off with Kee. After Luc leaves them, Patric hums a song before he shoots the Russian.
It sounded like a song from Pirates of Penzance. Anyone know if that was it, or if not, what it was?
Also I thought this was a really great movie. Alfonso Cuaron should be nominated for an Oscar. And the movie should get best picture. The extended shot was supercool. Rant Alert! Oh and this rule that IMDb has about requiring 10 lines for a post is the stupidest rule that I have ever seen