HERE'S a subject for investigation: mockumentaries – when did they start, and will the invasion end with the ubiquitous format taking over TV?

I would trace the beginnings to the 1984 film This Is Spinal Tap. In Rob Reiner’s classic comedy, written by Christopher Guest, Reiner (also starring), Michael McKean and Harry Shearer, the cameras followed a heavy metal band on tour, their triumphs and tragedies but mostly their regular bouts of humiliation, including getting lost en route to the stage.

It was such a hit that imitators were sure to follow, and it turned out that television, with its love of cheap to make fly-on-the-wall shows, had a lot to mock, from programmes about office life (The Office) and the BBC (W1A), to urban pirate radio DJs (People Just Do Nothing). Viewers had seen enough traditional takes on institutions to slip easily into the joke, and the style worked across the globe.

Cop shows have been particularly fertile ground for documentaries and their naughty twins, mockumentaries. So it was only a matter of time before Scot Squad (BBC Scotland, Thursday) put on the blues and twos and raced on to the scene in a 2012 pilot, followed by a full series two years later.

The sixth series of Joe Hullait’s creation finds many familiar faces returning, including Chief Commissioner Cameron Miekelson, traffic officers McKirdy and Singh, country bumpkin cops Jane and Charlie, and not forgetting Office Karen, the long-suffering desk sergeant, and Bobby, the member of the public who worships her across a preternaturally high counter.

There is one notable new face in the sixth series, though I must say “no comment” on any further detail lest it spoil the surprise.

Scot Squad works so well because it sticks to tried and tested characters while not being afraid to introduce new ones (Archie Pepper as the techy cop who can work the internet, for instance) and developing others (we’ve watched Ken Beattie go from a volunteer cop to an acting sergeant, making every mistake in the book along the way).

Long may Ken and his colleagues continue to protect (sort of) and serve (after a fashion). If the daft delights of Scot Squad have somehow passed you by there are lots of past episodes and mini-specials available on iPlayer.

This is Spinal Tap creator Christopher Guest also wrote, directed and starred in Best in Show, a mockumentary movie about show dogs and their ferociously competitive humans. At first glance, Pooch Perfect (BBC1, Thursday), a talent competition for groomers, would seem to be a programme after Best in Show’s heart, but I assure you it is perfectly serious. I think.

Hosted by Sheridan Smith and Stanley the dog, Pooch Perfect is from the same kennel, as it were, as The Great British Bake Off/Sewing Bee etc. It brings together 16 groomers, all competing to win the “Golden Stanley” trophy by impressing the judges. Each contestant takes on two challenges: a traditional breed makeover, and a more freestyle trim.

The dogs involved have been through an audition process to make sure they like being handled. One American cocker spaniel I know definitely would not have passed the test. He goes into the groomers like a Tasmanian devil, and only after much coaxing and cooing does he give in to a hair cut.

There surely cannot be any more hobbies or jobs that lend themselves to the “Great British” title unless the format goes niche. The Great British Window Clean anyone? Or Britain’s Best Traffic Warden, maybe?

Gordon Buchanan has one of the best jobs in the world, and he works so hard at it you don’t begrudge him for a minute. The Scot’s speciality is living as closely, and respectfully, as possible with animals the better to observe them. Cheetah Family and Me (BBC2, Tuesday) finds him in the Tswalu Kalahari Reserve in South Africa.

At the start of the 20th century there were 100,000 wild cheetah; today they are feared to number just 7000. Buchanan’s quest to find out the story behind those sorry numbers involves him following two mothers and their cubs. He does so not from the comfort and safety of a four-wheel drive, or with remotely controlled cameras, but on Shanks’s pony, carrying his equipment. Walking is rarely allowed on the reserve but he has been granted special permission.

It hardly seems such a treat as he walks nervously across the reserve in search of one of the mothers and her cubs. He soon spies the cubs, but no mum. “I’m a little bit worried she might be behind me,” he frets with some justification.

Also concerning him are the hyenas a couple of hundred yards away. Man, usually the hunter, could in short order soon be the hunted. Buchanan is genuinely awed by what he sees, which makes his films even more involving.