Chestnut
The OP was a request for examples of our cultural heritage, and I think we discussed what makes us English on another thread. I added some very English events like Chelsea Flower Show, Ascot, The Boat Race, Wimbledon Tennis, Henley Regatta, The Grand National, and more.
Then there's our musical heritage, famous 20th century popular music, The Beatles, The Stones, The Kinks, and more. And literature, Shakespeare, Dickens and so on.
The first steam train was invented in Wales in 1804. Quite an achievement, along with several other inventions.
Really, there are so many. As a country we have always punched well above our weight, probably due to our cold wet weather. We don't lie around sleeping all day, we keep busy inventing things, writing books, music etc.
Perfect summary!