The Lion and the Unicorn; Socialism and the English Genius by George Orwell.
If it's autumn, it's Orwell. This particular book is an old favourite, one of the very few books that I can reread.
Anyone interested in English society, culture, politics and history (or any one of the aforementioned) should read this book.
It's Orwell's 'why we fight', his perspective on the England of 1940, what's worth fighting for and what should be swept away at the next possible opportunity. I've been fascinated by it since I first read it over twenty years ago and whilst aspects of it are clearly dated, enough of it still makes sense when thinking about modern Britain (Orwell, the consumate Englishman, never refers to Britain throughout the book).
One of the things I appreciate about Orwell, which comes through in this book, is his own pragmatic approach to socialism and patriotism, the two are compatible and should be regarded alongside each other. He decries the right's ability to hijack patriotic feelings in order to pursue capitalist economic policies.
I could go on.
I have recommended this book to people (my wife included) who have looked upon the UK from the outside, some of them read it, appreciated it, but for others it seemed to not quite give them what they were looking for, then I realised, the audience Orwell was aiming for was the English working classes/reading classes of the 1940s. It's not a guidebook in that sense.
This book still means something to me as someone who cares deeply about the cultural, economic and political future of the UK, less of a naked patriot than I used to be (except when the World Cup rolls along) but still in love with the old girl all the same.