It's semi-final week for The Great British Sewing Bee

Although some of the audience of The Great British Sewing Bee know their way around an overlocker, many fans would struggle to sew a button back on a shirt, let alone make the whole garment from scratch.

So, why has the series been such a hit? Well, according to judge Patrick Grant, it could be that the sewing room is such a welcoming place to be. He says: “There’s a lot of telly that is based on the assumption that people want to see other people kind of put down, and we’re the opposite end of that spectrum.”

He adds: “It’s celebratory, and it’s instructive, and it’s inspiring – and also there’s a lot of my professional life that we get to talk about.

“Interestingly, we’ve managed to get some really important messages about sustainability and textiles and the way that people treat their clothes into the show, in a nice way that’s positive.”

His fellow judge Esme Young believes that people also like to see the contestants showing off their creative sides. She says: “I love how the sewers express their vision. They all have their own personalities, and that’s what they bring to the room.

“What we’re always looking for in students [at London’s Central St Martin’s College] is who they are, and I think that’s something that happens on the Sewing Bee. It’s about them.”

However, viewers may wonder whether the contestants occasionally get a little too creative.

Admittedly, sometimes the brief calls for the hopefuls to let their imaginations run riot. For example, in the recent art week, they had to make garments from repurposed canvases, before creating a made-to-measure inspired by surrealism.

But there may be weeks when more practical viewers wonder if it’s a case of style over substance – like when the sewers came up with surprisingly skimpy garments when asked to make rain wear.

Anyone who does fall into that category will be pleased with this episode as the focus is on all things utilitarian.

For the pattern challenge, Patrick Grant and Esme Young want the remaining contestants to turn old military uniforms into trench coats, while the made-to-measure involves making a boiler suit that perfectly fits their models.

There will still be a place for whimsy in the transformation challenge, as they create garments from old cleaning products, including cloths, rubber gloves and mop heads.

And of course, presenter Sara Pascoe will be on hand to lighten the mood a bit. That might be needed more than ever this week, and not just because of the utilitarian theme.

It’s also the semi-final, which means the pressure is on – and the judges will be extra picky, especially when it comes to the fit of those boiler suits.

Who will rise to the challenge and sew their way into next week’s all important final, and who will narrowly miss out? At least the person going home will know that they’ll get a fond farewell from the other contestants – as Patrick says, the sewing room is nothing if not supportive.