I keep seeing young blades in skinny jeans — nothing unusual in that — but with handlebar moustaches and cinched waistcoats. And then there are the girls wearing brass timepieces and black feathers in their cropped pixie hair. Some have a sort of Chimney Sweep silhouette with pointy shoes. It all adds up to a very Sherlock Holmesian look that’s spreading in ever widening ripples from the cobbled streets of Hoxton and Shoreditch.

Since Guy Ritchie’s new film about the super-sleuth was released, everywhere I look I see tweedy plus fours and deerstalkers, complete with Meerschaum pipes. Finally, last week, when I glimpsed someone on Clapham Common atop a pennyfarthing, it was clear: we’re now in the middle of a movement.

They’re a little surreal, certainly dramatic and have a sprinkling of the friendly punk about them — hence their name Steampunks. Many look like Jules Verne’s younger cousin — with a penchant for goggles and bowler hats. In extreme cases they might go by aliases such as Arthur Farthingale or Miss Violet Vaudeville. Many will read The Chap magazine and use the term “wizard!”.

Wizard Chaps are sartorial and really rather stylish. They get their clothes and accessories from Old Town, Gentleman’s Emporium, Savvy Row and other stores online. On the street their houndstooth comes from Dashing Tweeds, Dolly Dare or Beyond Retro, while their tartan comes from Vivienne Westwood and the brogues from Crockett & Jones. Authentic tweed was everywhere in the winter collections, from Prada to Margaret Howell to Rapha’s dedicated tweed cycling suit. Shooting jackets were worn all over central London. Even All-Saints is full of Victoriana, with its riding habit style, faded leathers and funked-up muttonchop blouses.

And then, on cue, comes Guy Ritchie’s Golden Globe-nominated film starring Geraldine James, Robert Downey Jr and Jude Law. Ritchie himself is a tweedy kind of fellow, and word has it that all the Holmes actors were given specially woven tweed caps as presents.

But what does it all mean, Holmes old chap? There’s usually a philosophical pulse behind a street style as tenacious and far-reaching as this. The key attraction, it seems, is the tremendous optimism of the Victorians and Edwardians. “The impression we get of the Victorian era, however inaccurate,” says Tom Wright, author of a blog called London Particulars, “is that they thought the future was going to be awesome.” It’s telling that optimism and hope for the future in London’s youngest and hippest finds its most potent expression in a vintage lifestyle.

They’re not Tories hankering for the old order but neither are they particularly politically correct: they rather like the dandy and the aristocrat, as well as the backstairs of Upstairs Downstairs. They are rationalists with enquiring minds who rely on sound logic. They appreciate science and technology, embracing iPhones in addition to old-fashioned technology such as single gear bicycles and airships. They have forward-thinking and creative frames of mind, and delight in having a go at everything. They celebrate the talented amateur, individuality and imagination. No retro-sexism is involved.

I should mention that the extreme side of all this can become alarming when it strays into Sebastian Horsley territory. (He’s the Victorian top-hat-wearing poet who dabbles in crucifixion). Likewise, Viktor Wynd’s Last Tuesday Society may be rather more decadent than most chaps would bargain for.

UK Steampunks can be hardcore whereas the style as seen at Steampunkthreads.com is increasingly hot in the US. It’s prettier over there.

A Steampunk exhibition at the Museum of the History of Science in Oxford runs until 21 February, showing extraordinary inventions by a group of international artists. Art Donovan, curator of the exhibition, says: “Steampunk is a science-fiction sub-genre, celebrating the arts and sciences of the Victorian era, with a very strong element of the what if’!”

Steampunks flirt with the macabre as a joke — a hint of Sweeney Todd and Jack the Ripper. They wear timepieces, goggles and pith helmets or high top hats, with eyeball accessories to add a dash of horror. The women either have shaved heads or an updo of ringlets like a colonial governor’s daughter.

Computer games that might captivate a New Chap or a Steampunk include Victoriana, Steamboat Chronicles, Rise of Nations and Arcanum. The soundtrack that accompanies the new what-ho! lifestyle comes from bands such as Abney Park, Mumford & Sons, Johnny Flynn & the Sussex Wit, E.S. Posthumus and Tom Waits. Perhaps a banjo or a hurdy-gurdy shanty beat accompanying a husky voice, with a dash of honky-tonk piano.

“The Steampunks try to marry Victorian dress and attitudes with modern technology,” says The Chap magazine editor Gustav Temple, “so it’s a sort of science-fiction version of the Gothic movement. I personally am all in favour of people dressing in Victorian clothes, as they are the very antithesis of contemporary fashions: complex, highly-structured, difficult to fasten and unfasten and, above all, rather foppish. I really cannot see dandies ever wearing cargo pants or sensible fleeces.”

Any day I’m expecting stage revivals of Victorian melodramas such as The Streets of London or Trilby (complete with Svengali) by George du Maurier.

It’s all a welcome antidote to anything thoughtless or bovine which lacks a certain depth of field, and certainly during the dark days of recession, New Chapism makes the future look much brighter.