Cool thread.That is a very classic garment and Burburry makes quality products. If you are worried about the "formality" of the garment, dress it down with jeans or chinos, and suede shoes or loafers. Avoid red pants, ascots, and french cuffs or you will look like a character from a British television show. I have a long thread on the Fashion Forum called "Blazers, Blazers, Blazers" containing many photos which may give you ideas on how to wear it.
I'm kinda with the "don't dress it down crowd" I get tired of seeing people in blazers and teeshirts, and blazers with worn jeans.