Long before Sherlock, Tinker Tailor or this week's Parade's End, the actor has won plaudits for his work on stage and screen. And his success has had nothing to do with going to Harrow

While being delightedly force-fed 17 days of splendid drama, one annual question has remained resolutely unasked in medialand this August: when will the silly season start?

Worry no more. It kicked in almost as soon as the last firework fizzed out over the last athlete's hangover. It kicked in with something of a confected row over Benedict Cumberbatch – yet a row that has puttered on, because it's about one of those British things about which no consensus can ever be reached yet on which everybody wants an opinion: class. Or Class

On BBC's Breakfast, there were still talking heads debating whether Cumberbatch had been right to "moan" about the occasional sniping he got for being a "posh" actor in this country. The responses were predictable enough. The nicely chippy northern woman declared it "vulgar" of him to even voice a complaint through his mouthful of privilege; the etiquette lady, trying to defend him, said his accent quite possibly held him back from some roles, such as anything involving Danny Boyle. It hasn't, incidentally, most notably when peeling off all on stage for that director's Frankenstein. But if those responses were relatively knee-jerk, that's as nothing to the twitterati, some with something interesting to say about class, a great many without, almost all hampered by the simple Chinese-whisper effect of only having heard that Cumberbatch said something moany about being picked on for being posh.

Let's look at what he actually did say.

Interviewed for Radio Times by Decca Aitkenhead, he talked about sudden real post-Sherlock fame, touched on his personal life and lucidly compared the similarities and differences between that role and the one he brings to our screens soon this Friday, that of Christopher Tietjens in Ford Madox Ford's tetralogy Parade's End, by all early accounts winningly adapted by Tom Stoppard. Both well-spoken, tall, English and Edwardian – in soul anyway, even though Cumberbatch's Sherlock has been so vibrantly updated – and variously tortured gentlemanly souls. But Christopher is taciturn and there is, as Cumberbatch put it, "none of that hyper-articulate mental vomiting. I think people might think, 'Why would he want to do that, because it's nothing like Sherlock?' But that's exactly why."

Then, in some final throwaway comments, he touched upon, or was invited to touch upon, "posh-bashing", and said that sometimes, mainly as a consequence of having been to Harrow, he has been "castigated as a moaning, rich, public-school bastard, complaining about only getting posh roles". Aitkenhead goes on to say: "As he's one of the most gifted, intelligent and likable actors this country has produced, I'm not surprised he can't even be bothered to engage the attack. 'It's just so predictable,' he sighs wearily. 'So domestic and so dumb.' I just hope he's not serious when he adds, 'It makes me think I want to go to America.'"

And there you have it. A half-hearted sigh about being castigated for complaining about only getting posh roles, and what sounds like an end-of-interview joke. Radio Times – perhaps surprisingly for a publication normally viewed as reliable, comprehensive but a bit… Auntie – has, for the past year or two, been knocking out many interviews that have produced the lead item in the next day's papers. They are not averse to taking the slightest of controversies from a celeb's mouth and, while never presumably being actionably inaccurate, still flamming it up to the high heavens. So you can be sure that, had Cumberbatch indulged in any serious kind of rant about class, or seriously "threatened" to go to America, it would have been worked into the intro, if not the headline. And from this, our nation of point-missers erupted into an orgy of castigating him for moaning about only getting posh roles. Which he hadn't.

The problem, of course, is confusion over class: over its very definition, and, in these austere times when we most definitely are not all in it together, over class envy. As soon as John Major pronounced that class was dead, he was condemned – not just for the slightly flatulent wishlist pabulum that clearly wasn't true, but, more crucially, for the flattened vowels in which he said it. Since then, snobberies and ignorances have unwittingly conspired to keep the fluid truth as murkily unknowable as in those early 90s. Poor Benedict even got a mention from the platform from another occasionally misunderstood cove, Michael Gove (like Cumberbatch, another scholarship boy), when he was named, alongside other actors such as Tom Hiddleston and Dominic West, a good handful of leading comedians, the 2010 Mercury winners, England's rugby team, etc, etc, as being inordinately unrepresentative of Britain as a whole, thanks to their fee-paying educations. But Gove – again, read it more carefully – insisted: "It is undeniable that the individuals I have named are hugely talented."

Rather, he was having a passionate pop not at them but at the "morally indefensible" strategy of so many other schools, which allow pupils to leave unable to read, write or add.

But Ben Carlton, as he was once, is now, wittingly or not, part of the usually inane national debate on class and one can only assume his wide-sloping, 36-year-old shoulders have enough heft to cope. Friends say there's not a twitch of doubt about that: he is described as intelligent, yes, but also exuberant, frank, fun and resilient. Both friends and interviewers have spoken and written too of the professional dedication: one second, you've got a relatively young man with an… interesting face – he happily admits to have been described as sexy sloth, startled meerkat, hammerhead shark, but no description prevented him walking away last year with various "sexiest man" and "man of the year" titles – chatting away in a T-shirt at rehearsals, then, on "Action!", transforming those planes of his face in half a second into embodiments of haughty unreason, cold anguish, cruel sarcasm or heart-melting kindness.

It was his agent who suggested he revert to his real name. His father, Timothy Carlton Cumberbatch, and mother, Wanda Ventham, are both actors. "A new agent suggested I go back to Benedict Cumberbatch. I thought it sounded a bit bumbly and messy, but they said it's a great name, it will get people talking about you."

As it did, as did his acting. Long before Sherlock, after Harrow and then swerving becoming a barrister (his first idea) to study drama at Manchester, he was winning plaudits for performances in the likes of Hedda Gabler (Olivier award nomination) and Tipping the Velvet, Tinker Tailor and his mesmerising portrayal of a young Stephen Hawking, in the run-up to which he met the scientist and talked to a number of motor-neurone sufferers: he apparently pre-prepares to the nth degree, reading, for instance, the works of a Golding or a Conrad (and now Madox Ford) before even venturing into the studio.

He is obviously grateful to the sudden mad leg-up Sherlock has given him, has spoken at length about his admiration for the writing, even his love for the character, and there's no doubt about the transformation in recognisability – as Sherlock writer Steven Moffat has said of this: "Sean Connery was nowhere before James Bond." HBO, who co-produced Parade's End with the BBC, was reportedly wary of him because no one knew who he was: they were sternly told "but they will". And they certainly do. More impressive is the fact that, before the magical pairing of Cumberbatch with Martin Freeman in Sherlock, someone thought those two would work well together in the forthcoming The Hobbit – Freeman as Bilbo, Cumberbatch as the dragon Smaug.

There is, as Cumberbatch admits, a slight danger of stereotyping. He loves Sherlock, doesn't want to be defined by it forever and consoles himself with the thought that "no one calls George Clooney 'Doug Ross' any more". For the moment, however, he and we are happily stuck for a bit longer with his personification of the most arrogant sociopath ever to trip down Baker Street and later this year/early next will be able to engage in a massive national debate that is actually worth having. How on earth did Sherlock manage to fake his own death?