LONDON—The adventures of the honey-loving bear “Winnie the Pooh” have captivated children—and their parents—for nigh-on 100 years. Fans now have a chance to own a central piece of Pooh’s history, when a countryside bridge from southern England goes up for auction next week. The author of the hugely popular Pooh series of books, A. A. Milne, often played with his son, Christopher Robin, at the bridge in the 1920s. It became a regular setting for the adventures of Pooh and his friends in the series that launched in 1926. “Offering it at auction is probably the biggest opportunity globally for people to reach out and be able to buy it and put it in a museum,” said James Rylands of Summer Place Auctions, which has previously auctioned items including 20 tons of the Berlin Wall. Rylands described the bridge as “one of the most important iconic literary objects there is,” …