(Before I start my list, let me clarify that these are the things I found weird when I first moved to Britain -- and still do, in some cases. I'm not saying Brits are weird for doing these things.)
Mince pies at Christmas - Can anything be more disgusting than horrible stodgy pastry stuffed with squished raisins and dates. Blek.
First-class and second-class post - Seriously, what is with that? Even the post must be sorted according to class?
Windows without screens - Leaves can blow in! Bugs can circulate! Windows need screens!
The Queen owns it all - Even if you buy a flat (in London, anyway), after 999 years it reverts back to the Queen.
No tax! - Now this I love. OK, there is tax, but at least it's rolled in to the price.
Tell the cabbie where you're going before you get in - Once you're in, they can't refuse your fare so you need to flag them down, then lean through the window and then tell them where you want to go.
More to come in future posts!