Inside the Supermarket (BBC1, 8pm)

NEW series. Documentary going behind the scenes of Sainsbury’s. After a challenging Christmas, the staff go all out to maximise profits with their flower sales over the Mother’s Day weekend. Plans are also made to sell a birthday cake to celebrate the company’s 150th year of trading, bringing in Claire Ptak, the creator of Harry and Meghan Markle’s wedding cake, for ideas.

Plus, last year CEO Mike Coupe announced a possible merger with Asda. Will industry regulators give the company the go-ahead to become the biggest supermarket in the country?

London Calling: Cold War Letters (BBC4, 8pm)

BETWEEN 1955 and 1975, the BBC’s World service programme Letters Without Signature broadcast letters which gave voice to the silenced people of East Germany by inviting them to secretly write into a radio programme. Listeners wrote in their thousands.

This film examines the impact of the show on both the people of East Germany – who faced imprisonment if discovered – and the show’s producers in London. Cameras also focus on its mysterious presenter, Austin Harrison, who announced different postal addresses every few weeks at the end of the show.

Giri/Haji (BBC2, 9pm)

AN ambush on a Soho restaurant ends with the Mori brothers on the opposite sides of a frantic gun battle – and prompts a series of flashbacks in which Yuto relives the split-second decisions that brought him and Kenzo to this point.

Fourteen months ago, Yuto realised he was destined to always be bad when yakuza boss Fukuhara dispatched his best man, Jiro, to recruit him.

But he also realised that unlike his brother, Fukuhara believed in him. Crime thriller, starring Takehiro Hira, Yuko Nakamora and Kelly Macdonald.