The Bluebell Railway was the first standard gauge railway preservation society opening in 1960. Since then it has gone from strength to strength and is now a thriving concern. Check the Bluebell Railway's website for opening times etc.
Originally only the eight kilometres (five miles) between Sheffield Park and Horsted Keynes were preserved, and trains used to crawl between them, spinning the journey time out to 15 minutes or more.
The long term plan was to reopen the line to East Grinstead, and in 1994 the line was extended to Kingscote allowing the trains to be worked in a much more realistic way.
Having shifted 300,000 cubic metres of garbage out of Imberhorne Cutting, the line through to East Grinstead was officially opened on 23 March 2013.
Frequently used as a film set, the Bluebell just about manages not to feel like one. However, if I have a quibble (and this wouldn't be the Strolling Guides site without a quibble) if anything everything is all too immaculate. It's certainly very different from the worn out post-war British Railways of the 1950s that I remember.