The Piano (Channel 4, Sunday, 9pm) is back, promising new station venues, fresh amateur hopefuls ready to make a public piano sing, and the same judges and presenter in Lang Lang, Mika and Claudia Winkleman.

One of the ratings smashes of last year, bringing in some three million viewers, The Piano was a word-of-mouth hit for Channel 4. Series one was followed by a Christmas special and the commissioning of two more runs.

The 2023 itinerary took in Glasgow Central, Birmingham, Leeds and London St Pancras; 2024’s includes Edinburgh and Manchester.

Channel 5 has gained a reputation recently for turning news stories into documentaries at lightning speed. Wonka: the Scandal that Rocked Britain, about the farcically awful “Willy’s Chocolate Experience” event in Glasgow, was one such production.

In comparison, the story at the centre of A Very British Sex Scandal: the Love Child and the Secretary (Channel 5, Wednesday, 9pm) seems like ancient history at first. Yet the tale has lost none of its power to shock.

The year is 1983, the Tories have won a landslide election victory on the back of the Falklands War. The party chairman, Cecil Parkinson, already a favourite of Margaret Thatcher, is credited with the win. The Prime Minister offers him the job of foreign secretary, one of the four great offices of state. Not bad for the son of a Lancashire railway worker.

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Parkinson must have been delighted, but he also had to tell “the boss” about a situation in his private life that would embarrass the government if it came out. He had been having an affair with his secretary, Sara Keays, and she was pregnant with his child. Thatcher responded by giving him trade and industry instead of the Foreign Office and kept him in the government.

The story did eventually break, just before that year’s party conference in Blackpool, and it was the huge scandal Parkinson feared. Would he resign or be sacked? How could he stay?

Jonathan Stiasny’s film, featuring interviews with some of the major figures of the time and the top journalists of the day, ably captures the excitement of the chase as Parkinson tried to cling on.

More details emerged. Keays gave an interview saying Parkinson had twice asked to marry her during their 12-year relationship but had changed his mind.

The conference had been ruined, questions were being asked about the Prime Minister’s judgment in keeping him in a job. He had to go, and did so with cries of “poor Cecil” to soften the blow. As Edwina Currie says, “I’m not sure anyone was saying poor Sara.”

It was clear that if Parkinson kept a low profile for a while, a return to front-line politics was not out of the question. Unfortunately for him, Keays had no intention of disappearing into the night, a woman shamed. Their daughter Flora had epilepsy and needed a lot of care. Parkinson, true to his word, refused to see the child. He paid maintenance but less than Flora needed.

In time, Thatcher brought him back, making him a Lord in the process. Ten years had passed and Keays was still popping up in the press from time to time. Parkinson had had enough. He secured an injunction to ensure that Flora could never be mentioned in public again. Anyone who did so, including reporters, ran the risk of being jailed.

Scots broadcast journalist Dorothy Byrne, who was making a film about Keays at the time, thought they would be able to overturn the “draconian” injunction but it was not to be.

The silencing of mother and daughter remains to Byrne “one of the greatest scandals in British political and legal life”. It is hard to disagree.

The story does not end there, as you will see in this fascinating 90-minute film. As well as telling a great story, Stiasny’s documentary functions as a “name that minister/reporter” quiz. See how many old faces you remember (and stay up for Portillo, now travelogue presenter, then Tory rising star).

It’s finale time on Interior Design Masters with Alan Carr (BBC1, Tuesday, 8pm). This year has been a fight to the finish, with some tense moments on Michelle’s sofa of doom for those who made the wrong design calls or simply screwed up (tiny chairs, tall table anyone?).

The setting for the finale is suitably impressive, design-wise - Blenheim Palace in Oxforshire, where two holiday lodges await the designers’ caress.

As one freshly painted door closes another opens as Scotland’s Home of the Year (BBC1, Monday, 8.30pm) returns for a sixth series. It does not seem that long ago since one of the programme’s trio of judges, Banjo Beale, was the winner of Interior Design Masters (it was 2022 in fact). Now look at him, an old hand already in SHOTY, and his own home makeover series to boot. Good things come to he who paints. And sands. And stencils …