As I write there's a moderately heated discussion on social media about whether Slow Horses is funny any more. I've not reviewed it here in the past because i've never seen it as a comedy. But the showrunner until this series was former stand-up comedian and Thick Of It actor Will Smith so it always had something of a slightly rippled humorous underbelly, particularly in Gary Oldman's scruffy boss Jackson Lamb, who made Albert Steptoe seem like an effete dandy.

But if season six has lost its comic mojo – and I don't think it has for one moment – it has gained something else thanks to new lead writer Gaby Chiappe, who seems like a pretty sound pair of hands when it comes to thrills and spills. Don't for one single moment expect me to explain the plot in any detail, thanks to embargos and my own stupid brain, just sit back and watch as familiar characters get bumped off and others, particularly River Cartwright (Jack Lowden, James Bond in waiting if the rumours are true) run for their lives through what feels like a constant hail of gunshot.

There are a few plots intertwined. Something dodgy with the Russians high up in MI5 (Kristin Scott Thomas as icily cool as ever, even when she is shaken and stirred at one point). There's also a dubious media mogul who has his own agenda. And then there are a couple of ruthless killers, male and female (MyAnna Buring and Kyle Soller), which has become something of a trope in recent dramas.

But even though Jackson Lamb himself never breaks sweat the pace fair crackles along. There are some old faces returning and a new one. Lenny Rush, always great value, pops up, but i don't think I'm allowed to say more about him at this stage.

At times the plot does creak a little - why is it the deadly assassins have no difficulty killing some people a mile off yet with other crucial members suddenly they can't hit a cow with a banjo. Then again that's always been the case with James Bond and we've been able to put up with it there so why not here?

And if the Slow Horses themselves are so rubbish they are only consignd to the most tedious cases, how do they somehow become involved in situations that threaten the very future of the country? And if they are so rubbish why do they crack those cases? And why is River's dad, played by Hugo Weaving a) American b) so nasty? I expect you know the answers. I'm mentioning this because I don't.

But somehow none of this really matters. Season six, based on two Mick Herron books, really motors. Ignore the title. There's nothing slow about these horses.

Slow Horses is on Apple TV

Picture: Apple TV