If you would like to read more about this subject, I would recommend the following: 

Literature:

• Watching the English, the Hidden Rules of English Behaviour by Kate Fox

• Fry’s English Delight by Stephen Fry

• The Development of English Humor Part One by Louis Camian

Internet sites:

•  http://en.wikipedia.org/wiki/British_humour

•  http://www.macmillandictionary.com/dictionary/british/

•  http://www.sarcasmsociety.com/irony/howtorecognizeirony

•  http://findarticles.com/p/articles/mi_m0QLQ/is_2008_May/ai_n25400112/

•  http://uncyclopedia.wikia.com/wiki/Johnny_Foreigner%27s_Guide_to_British_Humour