When T’Pau singer Carol Decker dons the monogrammed apron of MasterChef next Thursday there will be a lot riding on her ability to conjure up a two-course menu in just an hour – maybe even the future of public sector broadcasting.

The cooking contest, which also features Scots television presenter Jean Johansson as a contestant, is among the first of the reality television shows set to flood screens in the autumn.

It is tough out there in TV land. As viewing habits change, revenues fall, and audiences drift towards streaming services such as Netflix and Amazon, mainstream broadcasters are relying on reality shows to stem the flood and fill the coffers as never before.

Besides Celebrity Big Brother and Celebrity Masterchef, the schedules are being cleared for ITV’s The X Factor and I’m A Celebrity, Get Me Out of Here!

The motherlode of reality shows, Strictly Come Dancing, begins next month. Last year’s contest, won by Scottish actor Joe McFadden, was the show’s most successful ever, attracting an an average audience of 11 million every weekend.

For the BBC, the popularity of Strictly, Masterchef and their ilk acts as a buffer against criticism of the licence fee. BBC director general Tony Hall often points to the dance contest as the kind of original, home-grown content audiences want and the licence fee funds.

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Among those taking part in Strictly this year is Katie Piper, whose recovery after an acid attack was the subject of a Channel 4 documentary. Ms Piper, who now campaigns on behalf of fellow survivors and is an author and television presenter, was relieved when her presence in the line-up was revealed because it meant she could finally tell friends.

“It’s been so hard to keep a secret. I couldn’t use my own name for months. My codename was brie; everyone was cheese.”

Publicity campaigns are organised with military precision to extract maximum coverage. The top reality shows are valuable commodities that cost a lot to make, though far less than drama and documentary, and are expected to earn even more, with money coming from advertising revenue, phone voting and competitions, and selling formats internationally.

While audience numbers have been falling since the format’s heyday in the early 2000s, the right show can be the broadcast gift that keeps giving. Strictly Come Dancing has been sold to more than 50 countries. Big Brother is produced in 47 countries, including Albania, Ecuador, Nigeria and the Ukraine. Channel 4 paid £75 million to lure The Great British Bake Off from the BBC, a gamble that has paid off in tasty ratings. Reality shows pull in the audiences every broadcaster and advertiser wants: the 18-34 demographic, and families.

Celebrities are paid according to how famous they are, and how long they stay in the show. Strictly pays a flat rate of £25,000, according to the Sun, rising to £75,000 for semi-finalists and £100,000 for the winner. The same paper reported that Stormy Daniels, the adult film star who says she had sex with Donald Trump in 2006, a claim he has denied, would be paid £750,000 to stay in the Celebrity Big Brother house for a week.

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Non-celebrities can earn in other ways. The consultancy Frontier Economics estimated that contestants on Love Island who stayed for the whole series could earn more than £2 million in five years from appearance fees and sponsored social media posts. An Oxbridge degree, in contrast, was worth £815,000, analysts reckoned.

Then there are the other benefits from appearing on a reality show. Before The Apprentice, Donald Trump was just another New York property developer desperate to get into the gossip columns. The Apprentice gave him the kind of coast to coast exposure that made it possible to one day run for president.

Reality shows have been credited with everything from opening up totalitarian societies to breaking down cultural barriers. Strictly was at the centre of a row last year for pairing the Scots comedian, Susan Calman, who is gay, with a male dancer, Kevin Clifton. He said this week he would have “no problem” dancing with another man in the new series.

For politicians, reality contests can be an effective way of showing the public another side of themselves, either to boost their profile or carve out a new career after electoral defeat. Labour MP and Minister Ed Balls has managed to parlay a run on Strictly into a documentary series looking at Donald Trump’s America.

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But reality television can harm political careers as much as help them, as former Scottish Labour leader Kezia Dugdale found out. She was given a formal warning by her party for going on I’m a Celebrity without permission and while parliament was sitting. It later emerged she had been paid £70,000 for appearing in the show. From this she donated £5,100 to charity, plus £2500 from her Holyrood wages. Former MP George Galloway has never been seen in quite the same light since he pretended to be a cat on Celebrity Big Brother.

That is what makes reality television so popular with audiences: no-one knows how the contestants will fare till the cameras roll, whether they will soar like Balls or crash like Dugdale. Over to you in the heat of the MasterChef kitchen, Carol.