Steampunk is the most famous new trend that you've never heard of. To those in the know it's been around for years. For others, it's "Steam what?" It's certainly not new. The first steampunk (SP) convention took place in 2006: and the word was actually added to The Oxford English Dictionary in 2010.
Huffington Post UK
As Her Britannic Majesty Queen Victoria's Ambassador to the Ottoman Caliphate, Sir Donald Halliday-Crompton (known to his friends as "Hal") has had an interesting and varied life, both in the Diplomatic Corps and outside it. He has crewed a dirigible airship in fights with sky pirates and fought in the sands of Mars. He has been a spy for Her Majesty and can blend into any social occasion.
In the catacombs of Mars
I am an enthusiastic member of the Lincoln Steampunk Society, which is probably the biggest and most active Steampunk gathering in the UK. It's certainly the best known, because The Asylum, the largest and longest-running Steampunk festival in the world, is held in Lincoln every August Bank Holiday.
Inconspicuous at The Asylum
Steampunk is a subgenre of science fiction or science fantasy that incorporates technology and aesthetic designs inspired by 19th-century industrial steam-powered machinery. Wikipedia
Dene "Major Q" Woodman
Steampunk is Downton Abbey meets Meccano.
The Ambassador blending in.
Steampunk now encompasses a wide variety of input from a highly creative and artistic community. It includes writers, musicians, dancers, sculptors, model makers, costume makers and a host of other disciplines and skills. It has been summed up as; “Well, can you imagine what things would be like if the Great Exhibition had never finished?”
The Victorian Steampunk Society