Keep it light, Holmes, keep it light

So.  It's really happening.
Benedict Cumberbatch, the UK's premier posh-named film star (sorry Harry Hadden-Paton, no contest) has been called back from Hollywood for one more bromantic turn in the BBC's phenomenally successful Sherlock, the show that promoted him from Radio 4 comedy airline pilot to inclusion on Time Magazine's 'world's most influential people' list.  

Cumberbatch is the screen equivalent of salted caramel; it's actually a bit odd and you wouldn't think it would be that popular, but somehow absolutely everyone loves it.  Nobody is immune to his Tom-Ford-suited brand of witty smugness, I know avowedly straight men who would make exceptions for him as if not actually being into men is no defence against BC's charms.

And charming he certainly is, Mark Gatiss and Steven Moffatt's sharp reimagining of the eponymous sleuth could have been insufferable in the hands of an actor without Cumberbatch's magnetism, but as it is the first three series of Sherlock have been a complete joy.  However, I've got misgivings about series four.  The recently-released trailer is full of dim lighting, words of portentous doom and frowning.  Lots and lots of frowning.  At one point someone shouts 'For Christ's sake, Sherlock, it's not a game!'.  
Let's get this straight - it definitely is a game.

Here's how an episode of Sherlock works:
9pm There's a mystery of some sort
9:10 Sherlock strides in in his big coat and throws about a few mildly insulting wisecracks/amusing misapprehensions about social norms 
9:25 Watson looks exasperated, confused and possibly slightly turned-on
9:30 That very handsome police detective also looks exasperated, and generally a bit silly
9:35 Mrs Hudson calls everyone 'dear' and complains that the flat is messy
9:40 Mycroft sits behind his big desk and looks supercilious
9:45. Sherlock plays the violin (unconvincingly), mutters to himself a bit and finally solves the mystery with a dizzying series of deductions which frankly push the boundaries of credibility, and everyone toddles off happily to the real-world carnage of the ten-o'-clock news.
It's witty, clever, basically undemanding television.  

But it looks rather as though series four might have succumbed to the Bond/Batman/Harry Potter impulse to get 'serious' i.e. somewhat more moodily lit and much less funny.  When shows do this people start throwing around phrases like 'coming of age' and 'earning credibility' as though witty equals low quality and frowny and self-important automatically means critical acclaim.  
Not Sherlock.  It's already got serious critical acclaim (including three BAFTAs and seven Emmys to date) by being a bit daft, decidedly tongue-in-cheek and essentially light.  It's genuinely joyful entertainment, not serious cultural commentary, and trying to change that might just ruin the spark of magic that makes it one of the best things on TV.

So keep it light, Holmes, you're not saving the world, you're just making it that bit more fun to live in.