Tonight’s TV: David Dimbleby’s huge series about the royal family | television

What is the purpose of the monarchy?

9pm, BBC One
“Are you a supporter of the monarchy?” David Dimbleby, who has reported on countless royal events, was once asked. He replied: “I am a professional in TV shows about the monarchy.” In this three-part saga, he examines the role the royals played – and predicts what will happen next. The opening episode questions how politically neutral the monarchy is and how much power its members really have, given, among other things, the letters written by King Charles III, when he was Prince of Wales, to Tony Blair, and Queen Elizabeth II’s agreement to suspend Parliament in 2019. He speaks to insiders, including David Cameron, and critics such as journalist Ash Sarkar. There’s one thing everyone can agree on, says Ian Hislop: “It’s the perfect soap, isn’t it?” Holly Richardson

Mary at 90: A Lifetime of Cooking

At 7.30pm on BBC Two
In this week’s series finale, Ghosts star Kiell Smith-Bynoe takes on the role of the perfect sous chef as Mary Berry expands on the fine art of hosting a four-course dinner party. Foodie fashions may have changed over 60 years in the kitchen, but getting friends together over good food is a constant source of joy. Ellen E. Jones

Celebrity MasterChef

8pm, BBC One
There are no eliminations today, but the group still needs to bring their A game to this final week of qualifiers, with challenges including Under the Cloche (turning one ingredient into the star of a dish), a blindfolded palate test, and a street food market – cooking their own dish for the drooling judges. Ali Catterall

Tommy: Good. The bad. Anger

9pm, BBC Three
A double bill for the by-the-numbers reality show starring Love Islander turned boxing pro Tommy Fury. The hand injury is a setback, but it gives Tommy time to focus on his personal life. Newly reunited with Molly Mae Hague, could a mobile home be just the thing they need? Hannah J. Davis

Cooper and Fry

8pm on Channel 5
The investigators head to an abandoned quarry where a man was found beaten to death. The trail leads them to a village locked in a David and Goliath battle for survival against a faceless water company – but who are the mysterious figures who seem to be following Cooper and Fry at every turn? Jack Seale

The most dangerous roads in the world

9.45pm, BBC2

This part of the travelogue, which sends celebrities traveling through high-risk motorways, features Derry Girls friends Jamie Lee O’Donnell and Saoirse Monica Jackson. It’s their fifth trip together in one year, but since it’s off-road through the Romanian mountains, it’s likely to be their most worrying. Alexey Duggins