Ukridge by PG Wodehouse. I hadn't really ventured out the Blandings/Jeeves/Psmith collections that much. Ukridge may be the funniest book I've ever read. He's also featured in another book 'Love Among the Chickens' - absolutely hilarious.
If you like these, you should try the Uncle Fred books. Of course almost everything by Wodehouse is a sublime masterpiece.
I am so glad to read this comment. Wodehouse is sublime in all what he wrote - if you end up reading Jeeves series, I would recommend Right Ho, Jeeves and Code of Woosters