What is it about British humour?

From time to time, people ask me if I like British humour (specifically television shows and the Python movies).  I usually respond, “I don’t know”.  They assume that I haven’t watched any, and we move on from there. 

The truth is more complicated.  I have watched some, and I like it, really I do, but I just can’t stand it for more than about ten minutes. 

This was driven home a few days ago when I watched the first episode of “A Bit of Fry and Laurie”.  Stephen Fry, Hugh Laurie.  I have become a huge Hugh Laurie fan because of the American TV show “House MD”, so I thought I’d give this a glance. 

And it’s wonderful.  Every sketch was excellent, and well done.  I loved all of it.  And I had to take a break after 10 minutes.  Not because I didn’t like it, or got offended, or had to go to the bathroom, or anything like that.  I simply needed a break. 

I have the same kind of reaction to Monty Python.  Good stuff, for ten minutes.  Any ten minutes, it doesn’t matter.  Then I start growing restless. 

Can anyone shed some light on this mystery?