Mum (BBC2, 10pm)

A bittersweet new sitcom gives Lesley Manville, the Bafta-nominated drama actress in BBC1’s River, the chance to go for laughs as a widow who is trying to move on with her life. The six-part series created by the writers of Russell Tovey’s comedy Him & Her appealed to Manville because she felt she was known for plying big emotional classic roles and this was a good chance to do something lighter that still had character and substance.

“I know my forte wouldn’t be an out-and-out comedy where you go, ‘Here’s the joke – boom boom’. However, what I love about Mum is that, every now and again, you get this laugh that’s more about recognising a situation than the gag itself. It’s subtle and gentle,” she tells TV Times about playing Cathy.

Surrounded by relatives and quirky friends, who she tends to indulge, there’s also an adored son Jason (Sam Swainsbury) who introduces his nice-but-dim girlfriend Kelly, a role filled by Geordie actress Lisa McGrillis. Manville feels Cathy gets side-tracked by feeling that other people need looking after.

“But, we had to make sure that she had a wit about her too. She’s quietly laughing at all these mad people, but she also has a lot of patience. My son Alfie (27, with ex-husband Gary Oldman) is a similar age to my screen son. She’s very pragmatic and comfortable in her own skin as I am, but I’m not as patient as her. I’m more judgemental,” says Manville.

In this opening episode, it's January and the morning of the funeral, and Cathy's family has gathered at the house to await the cars. They should be a source of comfort, but instead they could add to the widow's overwhelming emotions, as she finds herself drawn into a battle with her brother's partner and enduring an awkward meeting with her son's new and somewhat overly enthusiastic girlfriend.

At least she can rely on her friend Michael (Peter Mullan, another actor who is perhaps more associated with hard-hitting dramas) to help her through what is set to be a very difficult day.

Food Detectives (BBC2, 7.30pm)

ALICE Roberts carries out an experiment to test the claim that chillies can help a person lose weight. In a sealed chamber a volunteer eats a meal containing chilli and one without and over the course of nine hours their metabolic rate is monitored to reveal any difference in the burning of calories. Chef Tom Kerridge travels to Dunoon, in Scotland, to help a viewer cook the perfect steak, while Sean Fletcher examines nutritional labels on food packaging, highlighting why the current system may be failing in its objectives.

Unreported World (Channel 4, 7.30pm)

SHAUNAGH Connaire visits the Islamic Republic of Iran to take a look at the reality of life for its younger citizens. With nearly half of 18 to 35-year-olds single, the country is in the midst of a marriage crisis. Many young Iranians are shunning marriage and enjoying newly popular ways to meet people, such as Instagram. They are also seemingly finding it hard to combine the search for love with commitment to the rules of Islam and respect for the traditions the older generation believe to be important.

Revealed - The Truth About the Holy Grail (C5, 8pm)

THE legend of the Holy Grail has taken many forms throughout history, but it has always identified the Grail as the cup Jesus drank from during the Last Supper. However, the whereabouts of the cup has been a subject of intense speculation for centuries. Back in 2011, Le-n University medieval history lecturer Margarita Torres and art historian JosZ Manuel Ortega del Rio discovered two remarkable Arab parchments at Cairo's University of al-Azhar that appeared to offer important new clues. However, in Europe alone there are 200 supposed holy grails, so is the precious goblet in Le-n's San Isidro basilica the real one? And if not can the mythical chalice ever be tracked down?

Viv Hardwick