THE documentary market has become one of the toughest to break into. It is not just that there are so many around, although looking at Netflix it seems like there is one born every minute. The trouble lies in trying to find new ways to tell stories, particularly when the subject has been as well covered as Dunkirk.

It is only two years ago that the 80th anniversary was marked, and before that there was Christopher Nolan’s spectacular recreation of events in his 2017 movie.

Dunkirk: Mission Impossible (Channel 5, Saturday, 9.30pm) is, on the face of it, a straightforward account of those fateful days in May-June 1940, complete with talking head historians and maps. Lots of maps. What makes this three-parter stand out is its main presenter, JJ Chalmers.

As a former Royal Marine and veteran of the war in Afghanistan, Chalmers brings a singular perspective to the story, one that comes into its own when he is describing the moment a young British soldier was hit by shrapnel.

“I know only too well what that’s like,” says Chalmers, who was severely injured in a bomb blast in Afghanistan.

“Nothing prepares you for a moment of extreme trauma like that. The wash of emotions and feelings that comes across you in a split second is like nothing I ever hope to experience again. You’re confused. You can’t believe it has happened to you. You are in pain. And all of this is happening in a split second when chaos continues to ensue around you.”

The Scot’s military training also tells when he dons a uniform of the time to recreate what it was like to wade into the sea and wait for boats. There were no performance fabrics then, just an itchy wool get up that took forever to dry. As he acknowledges, he is only in the freezing water for minutes, while the troops could be there for nights on end.

While Chalmers is in France crossing the same countryside the British troops would have walked through, German bombers dogging their every step, co-presenter Raksha Dave is in Britain detailing how the evacuation was planned and executed.

Such was the success of the parent show, Your Home Made Perfect, it was inevitable that offspring would quickly follow. Your Garden Made Perfect (BBC2, Friday, 8pm) applies the same techniques and format: two experts present clients with competing plans which are brought to life via virtual reality. Clients choose a plan, in come the builders, job’s a good un.

Instead of worktops and skylights, the talk in the spin-off show is of chill out areas, barbecue zones and creative planting. This week’s episode features a large garden that’s lovely but unsuitable for a couple with young children, one of whom has autism.

Though the budget of £60,000 is the stuff of dreams for many, the emphasis is on the practical, and there are lots of ideas to try out on your own muddy patch.

The finished result meets with instant approval, with one young customer in particular keen to explore this new green world.

Now, I can’t have been alone in having a funny feeling while watching last week’s Call the Midwife (BBC1, Sunday, 8pm).

All was birthing business as usual in London’s East End, except Dr Turner, Sister Julienne and Nurse Corrigan (Stephen McGann, Jenny Agutter, Megan Cusack) had gone off to a conference in Chelmsford to learn about epidurals and other new-fangled stuff.

As they got on the train home to Liverpool Street the carriage was crowded with football fans. “So glad I didn’t drive,” chuckled Dr Turner. “Much easier by train.”

Sister Julienne smiled beatifically (she doesn’t do any other way), glanced at the footie fans, and said: “We may be in for an interesting journey.”

Can't say if it was the suspiciously portentous dialogue, or the fact Sister J was reminiscing with the tea lady about times past (never a wise move), but something was afoot. Sure enough, there was a train crash. When last seen, Sister J and the doc were trapped in the wreckage and Nurse Corrigan was part of the walking wounded.

Thus the scene is set for the series 11 finale. The Radio Times decided now was not the time for putting viewers through the wringer like this and splashed the story on the cover of next week’s magazine. “DON’T DO IT” screamed the headline, “Bump off Sister Julienne? No! A nation begs Call the Midwife creator Heidi Thomas for mercy.”

A tad strong perhaps, but fans will understand. Interviewed by Jane Garvey, Thomas was giving nothing away, thereby ensuring another large slice of the audience pie for the finale. Don’t mess with the midwives.