My friend Fran has occasional film evenings called War & Meat, when a group of male friends will pile around his place to watch violent films and eat tasty animals. Hence I know what the combination of Zaitochi with meat and potato pie is like, and can recommend films to accompany haggis or black pudding.

I suspect that The Unit has its origins in a similar lads’ night in. Only, its hosts were Shawn Ryan, creator of awesome cop drama The Shield, and David Mamet, who wrote Glengarry Glen Ross and Spartan, two of the best films ever. Needless to say, Shawn and David are men’s men, and I don’t doubt that they ate something damn tasty together as they conceived their joint venture, a tv series which tells the story of a covert military operations unit, and the wives of the men who make up its ranks.

Some of the episodes are written and directed by David Mamet, though I’m not sure they can be reliably said to be much superior to those written by other members of the show’s team. The feel of Mamet and Ryan’s creation runs through the whole, regardless of the individuals involved. The show’s Special Forces heroes snatch hostages from under the noses of incompetent FBI agents, go under deep cover in Afghanistan and are nearly let down by their lack of affinity with donkeys, and plant bugs in situations that smoother espionage professionals shy away from. It’s compelling, elegantly plotted stuff, and thoroughly enjoyable in a way that the more cynical Spooks shies away from.

Please don’t read that as a dismissal of Spooks however: instead, it’s an endorsement of the clever and credible multi-faceted plotting of the show’s most recent series, all about the role of Iran in the modern world, and the response of existing powers towards it. Unusually for a tv show, Spooks gets better with every series: I was none too fussed by the first few, but have been increasingly gripped by the way that the plots are fuelled by high stakes beats derived from what feels like detailed research, and the necessarily painful and compromised decisions that the protagonists are drawn into.

Sure, it has its less credible aspects too, mostly to do with the interpersonal relationships of its characters, but this is still television of a very high calibre. And season six was the show’s strongest outing yet, save for the last episode, when the Iranian storyline finished and a weaker story about the Venezualan president was featured.

The problem for Spooks is where to find more characters, since they’re more than prepared to sacrifice ones they’ve spent a lot of time developing into three-dimensional personalities. And where are you going to find characters that have the guile and resourcefulness to survive in the world of international espionage?

I think I have the answer. She’s well known to tv viewers already, has a certain lads’ mag appeal that can only boost the show’s ratings, and has recently demonstrated a lethal ability to get what she wants in a no-holds barred battle of wits with her brother. I’m talking about Sarah Platt, who has managed to escape Coronation Street and indeed Weatherfield, and is now living in Milan after planting drugs on her brother David – who everyone thought was the cunning one, but is now shown up as a rank amateur - following his attempt to derail her wedding. More than the journalist character recently introduced into Spooks, Sarah Platt has the capacity to use deceit in the pursuit of her objectives, and a career in espionage has got to be more compelling for her than working in whatever bit of a spurious family business has taken her to Italy. Or be braver still and go for the double – hire David Platt too, and you’ve got an agent who’s prepared to kill himself to get the job done, and whose smouldering antagonism towards his sister will work just as well on Spooks as it did on Coronation Street.